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red rays. These could be distributed through the solution only by diffusion of the activated hydrogen ions or hydrogen-ionester complexes from the surface into the interior. The question, however, of the possible activity of infra-red rays is so important that duplication and amplification of such
experiments should be undertaken. If such be done the choice of a reaction system through which the radiation might readily penetrate would facilitate the attainment of decisive experimental test. We hope to take such problems in hand a t an early date.
~~
INDUSTRIAL AND AGRICULTURAL CHEMISTRY IN THE. BRITISH WEST INDIES, WITH SOME. ACCOUNT OF THE. WORK OF SIR FRANCIS WATTS, IMPERIAL COMMISSIONER OF AGRICULTURE By C. A. Browne N. Y.SUGARTRADELABORATOKY, 80 SOUTH ST., N E W YORX,N . Y . Received October 5 , 1920
The casual traveler, who makes his first voyage among the West Indian Islands and views from his steamer the crumbling walls of old fortresses, or the remains of stone mansions, acquires at the outset the feeling of a departed civilization. This first impression is intensified by the ruined walls and towers of ancient muscovado sugar works, which, according to the lines of Grainger, the poet of St. Kitts, were once lit up a t night by “far-seen flames bursting through many a chimney.” I t is only when the vessel steams past these scenes of desolation into the harbor of Basseterre, the former home of this poet, and the smoking stacks of a modern sugar factory come into view that the impressions of decadent or vanished industries are dispelled. The present paper is an effort to tell briefly the story of this change from an old t o a new order of things, in which transition CHEMthe efforts of a distinguished member of the AMERICAN ICAL SOCIETY have played a prominent part. With the abolition of slavery in the British West Indies in 1834, the old industrial system of these islands came to an end. The production of sugar, which had always been the chief source of wealth, began to decline, partly from lack of labor and partly from unequal competition with the more scientifically conducted beet-sugar industry of Europe, which marked its phenomenal rise from the date of the abolition of slave labor in the colonies. The inequality of this conflict was later enhanced by the favoring export bounties which beet sugar received, and had it not been for the high prices of sugar, which existed for 2 0 years after the outbreak of the American Civil War, the declining sugar industry of the West Indies would have completely disappeared. The over-stimulation of the beet-sugar industry by bounties and premiums soon had, however, its inevitable effect, and between 1882 and 1892 the price of muscovado fell from 7.3 cents t o 2.8 cents per pound. The industrial condition of the British islands was becoming hopeless, and appeals were made for assistance to the mother country, which for the 50 years followingthe abolition of slavery had shown a strange indifference to its West Indian possessions. This neglect had in fact become so marked that many planters believed their only hope to consist in political union with the United States. It was only with the growing development of the Panama Canal enterprise in the late eighties and the dawning sense of the future strategic and economic importance of the island approaches to this gateway of the Pacific that Great Britain began to take a renewed interest in her tropical colonies. From that time until the present, increasing efforts have been made to improve the industrial, economic, and educational life of the British West Indies. Botanic gardens, experiment stations, and other scientific institutions were established, among the earliest of these being the government laboratory in the island of Antigua, which began its work on Jan. I, 1889, and of which Dr. (now Sir) Francis Watts, a graduate of Mason College, Birmingham, assumed charge as analytical chemist.
IMPROVEMENTS I N SUGAR MANUFACTURE
One of the first investigations which Dr. Watts instituted on beginning his new duties was a thorough examination of the field and factory methods of the sugar industry. His chemical training convinced him that if the cane sugar of the West Indies had to compete with the more scientifically manufactured beet sugar of Europe, the wasteful antiquated processes of the little muscovado factories must disappear. In a little work, entitled a “Manual for Sugar Growers,” and in various reports, Dr. Watts opened the eyes of the West Indian planters to the enormous losses which their small factory system involved, and as a remedy suggested the erection of large scientifically managed central factories. The idea was favorably received but opinions were divided as to whether such factories should be under government or private control. After much discussion a working scheme was evolved, whereby a group of British capitalists negotiated contracts with certain estate owners in Antigua under which the latter undertook to supply, during a period of 15 years, the sugar canes grown on certain stipulated areas a t a price based on the current market price of sugar, coupled with a share in the profits of the factory and, ultimately, a share in the ownership of the factory itself to the extent of one-half. The capitalists formed a company with a capital of some $200,000, including a sum of $72,000, subscribed by the government. IVith thi? a small central sugar factory
OLD M U S C O V A D O
SUGAR
FACTORY, BRITISHW E S T
INDIES
capable of making about 3000 tons of sugar in a season, was erected a t Gunthorpes, Antigua. The success of the new enterprise was immediate, and the Antigua factory has now grown from a capacity of 3000 to 10,000 tons of sugar per season. In 1919, a t the end of the 15 years’agreement, the government cancelled its $72,000 subscription, its own income from the enterprise in the form of excess profits and exports taxes having exceeded $300,000. The contracting planters received during this time an average of 20 per cent annually on their original investment, and a t the end of the 15 years had turned over to
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them shares representing $ ~ ~ O , O O Oand approximately $go,ooo ta their credit on the company’s books. The belief that the Antigua central factory would be a pioneer object lesson for sugar planters in other islands was so well vindicated that a second cooperative factory was soon established a t Basseterre in the island of St. Kitts, and others in Barbados, Trinidad, and Jamaica. The success of these central factories has naturally had a most favorable influence upon the welfare of the islands, the laborers receiving the benefit in increased wages and the small farmers in the increased price for their canes. All this prosperity has resulted from the simple fact t h a t with the economies of the chemically controlled central system only about 9 tons of sugar cane are needed to make a ton of sugar, while with the primitive muscovado process 14to 15 tons of cane were required. The results of the Antigua factory for the years of its operation are summarized in Table I. TABLEI-RESULTS
OF THE ANTIGUA SUGARFACTORY
1905-7 3 Yrs.
......
1911-13
1914-16
1917-19
3 Yrs. 3 Yrs. Average Average Average
1908-10
3 Yrs. Average
3 Yrs. Average
92,302 9,970 12.67
85,690 9,586 12.79
Cane ground, tons. 27,106 Sugar made, tone 2,737 Sucrose in cane, per oent 14.17 Sucrose in bagasse, per cent 7.33 Purity of juice, per cent 87.60 Recovery of sucrose, per cent.. 68.43 Yield of sugar, per c e n t . . 10.03 Price of sugar, per ton. 849.68
........
................
...............
..
42,888 4,693 14.37
61,612 6,349 13.74
85.38
6.07
4.61 83.70
3.22 83.90
2.63 83.83
73.10 10.93 $56.42
72.18 10.32 $53.66
82.06 10.78 $69.60
84.15 11.20 $103.68
The results show that while there has been a marked increase from year to year in factory efficiency, as shown by the rising recovery of sucrose and the diminishing loss of sugar in bagasse, this gain has been offset by a progressive decrease in the sucrose content and purity of juice in the cane. The latter circumstance has given rise to the fear that the cane of Antigua might be undergoing a degeneration like that of the Bourbon cahe in the West Indies about 1890 and of the Cheribon cane in Argentina in 1916. The probabilities, however, are that the diminishing sucrose content of the sugar cane in Antigua is due to certain defects of the central system, especially in times of shortage and ascending prices, whereby cane cutters and planters, from being paid by quantity instead of by quality, send to the factory a large amount of cane that is unripe, diseased, trashy, or otherwise unfit for milling. The spoiling of cane by fermentation, as a result of delays between cutting and milling, is also no doubt responsible for much of the trouble,I a supposition which is confirmed by the fact that the fiber content of the cane a t the time of grinding has increased from its original value of 15 per cent in 1905 to 17 per cent. The excess of fiber in the sugar cane of Antigua, while insuring an extra sufficiency of bagasse for fuel, has its objection in that the difficulties of milling are vastly increased. This factor in an island of insufficient rainfall and inadequate water supply, such as Antigua, where maceration must be curtailed, necessarily impairs the recovery. The central factories of Antigua and St. Kitts were visited by the writer during the campaign of 1919. Both establishments are thoroughly modern in their equipment and the contrast between them and the few remaining muscovado factories, that were still in operation, was most striking. CANE
SIRUP
Ciosely connected with the sugar industry of the British West Indies is the manufacture of cane sirup or, as it is locally termed, fancy molasses. The process is generally carried out in the old muscovado factories, the primitive equipment of which is well adapted to the making of sirups. The steps of manufacture are in fact very similar to the operations of making 1 The deterioration in quality of cane supplied t o the factory has also been noted in St. Kitts and other West Indian islands. For a full discussion of the question see papers by Sir Francis Watts in the West Indian Bulletin, 16, 96, and 17, 183: also the paper by I,. I . Henzell in the Louisiana Planter, 62 (1919), 395.
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muscovado, the only difference being that precautions are taken to invert a part of the sucrose in order to prevent its crystallization in the container. The process, as the writer saw it carried out in Barbados, is briefly as follows: The canes are crushed by means of wind power between three vertical rollers, the juice from the mill flowing by gravity into a clarifying tank where it is heated with a little milk of lime, insufficient to neutralize the natural acidity. The limed juice after heating is allowed to settle, and the clarified liquid drawn off into a train of copper evaporating kettles, called tayches, heated by burning sun-dried bagasse. In the first evaporator the juice is treated with a bucket of cane juice that has undergone an acid fermentation, in order to invert a part of the sucrose. The boiling liquid is skimmed to remove impurities and during concentration is ladled from tayche to tayche until it finally reaches a density of about 36’ BC. hot, when i t is run into a cooler. The product when cold has a density of 42’ Be., is of a clear wine color, and has a most agreeable flavor. The composition of several grades of “Fancy Molasses” according to analyses made in the Antigua laboratory by Dr. H. A. Tempany’ is as follows: TABLE11-COMPOSITION O F “FANCY MOLASSES”
.............
I
Water. Sucrose.. Reducing sugars.. Ash Non-sugars.
I1
I11
19.7
19.8
IV
V
22.4 27.1 21 9 42.1 43.0 44.2 51 0 ........... 46.3 32.8 30.7 24.4 20.0 .... 27.3 ................. 1.3 1.9 1.5 3.3 1.8 ......... 2.7 3.5 5.0 1.0 5.3 TOTA I,.......... 100.00 100.00 100.00 100.00 100.00 Direct polarization. . . 39.9 35.0 35.1 36.2 47 5 Degrees Be. 41.5 41.2 39.0 41.0
.............
In Sample IV the evaporation was not carried to the proper degree, and in Sample V the inversion was not sufficient to prevent crystallization. A sirup of the so-called “two forties” standard (that is, having a direct polarization of 40 and a density of 40’Be.) will keep without crystallization, and this is the general aim of the manufacturer. It is unfortunate that so little of the pure cane sirup manufactured in the West Indies finds its way directly to the table. A large part of it is used by blenders for mixing with low-grade molasses, a good product being thus adulterated to improve an inferior one. It is the opinion of many West Indian producers that the only effective means of getting their sirup to the consumer in a pure recognizable form is to can the product a t the factory in sealed tins, upon which the name of the brand is stamped in raised letters. The activities of the government laboratory in Antigua have been directed t o the improvement of other industries besides those of sugar and sirup. The great dissimilarity between the different West Indian islands in soil, rainfall, and other climatic conditions has necessitated a careful study of the adaptability of each island to special crops and industries. The precarious condition of sugar manufacture in the islands, where the central system is not feasible, has also led to the encouragement of other agricultural industries. Of these we can mention only cacao, citric acid, essential oils, and rubber. CACAO
Next to sugar the most important agricultural enterprise of the British West Indies is the growing of cacao. The cacao tree becomes productive when about 5 years of age and, if in a healthy condition, will continue to bear from 40 to 50 years. Isolated trees may attain a height of 30 to 40 ft., although in cultivated orchards the maximum is not allowed usually to exceed 15 to 20 f t . The fruit consists of an elongated pod, containing from 20 to 50 or more beans or seeds, embedded in a pink colored pulp. When ripe the seeds with the adhering pulp are removed from the fruit and, after undergoing a process of curing or fermenting, are cleaned, dried, and packed for the market. 1
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Courtesy of the Louisiana Sugar Planter V I E W OF V A C U U M PANS AND
MULTIPLE EFFECTS,GUNTHORP&S SUGAR
In the process of curing, as observed by the writer in Dominica, the pulp-covered seeds are placed under cover in boxes, where they are turned over once or twice a day. The temperature of the mass begins to rise and in a few days attains a maximum of about 45’ C. The heating of the beans is the result of a fermentation of the adhering mucilage, the sour liquid or “sweatings,” which drain from the mass, being allowed to escape. Employment of this waste for vinegar making and other purposes has been proposed, but so far no successful method of utilization has been devised. After fermenting, which lasts from 3 to 7 days, the seeds are dried in the sun on large trays which can be wheeled on tracks under shelter in case of rain. As a result of the fermenting process the cacao seeds are not only freed from pulp, but a number of important chemical changes take place which improve the character of the product. The beans take on a brown-mahogany color, agreeable aromatic odors and flavors are developed, and the astringent tannin substances, which give the uncured beans a bitter taste, are modified or removed. The subsequent drying in the sun appears to promote the changes begun in the curing house, an effect which artificial drying by machine does not seem to accomplish. Artificial drying is necessary, however, in rainy localities in order to prevent the beans from becoming moldy and mildewed. The product must be dried slowly a t not too high a temperature; fans must also be used to insure circulation of air. Artificial
FACTORY, ANTIGUA
drying’ is most successful when the conditions of sun drying are imitated as closely as possible. The chemistry of cacao curing and the conditions of obtaining the most desirable aroma and flavor are a t present very imperfectly understood. As Knapp2 has recently pointed out, an important and most attractive field of chemical research here awaits investigation. Experiments to determine the chemical conditions of soil necessary for securing the most favorable yields of cacao were instituted by Dr. Watts, in association with the officers of the Agricultural Departments, in Dominica, in 1901,and the results of this work, which have been continued for nearly 2 0 years, throw a great deal of light upon the fertilizer requirements of this particular crop. These experiments, as summarized by Tempany,a show that by far the best yields under Dominican conditions are obtained from soils which have been mulched with a nitrogenous dressing of legumes, the decomposition of the organic matter thus supplied rendering available the natural reserves of potash and phosphoric acid already existing in the soil. From 3 to 5 years are required for cacao trees to acquire 1 G . Whitfield Smith, “Artificial Drying of Cacao,” West I n d i ~ nB u l letin, 2, 1 7 1 . 2 “Application of Science to Cacao Production,” J . SOC.Chem. Ind., 87 (1918), 468. “A Study of the Results of the Manurial Experiments with Cacao Conducted at the Botanic Station, Dominica,” West Indian Bulletin, 14, 81.
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Jan., 1 9 2 1
the maximum productivity occasioned by any particular method of manurial treatment. CITRIC ACID
The citric acid produced in the British West Indies is derived entirely from limes, the industry being confined mostly to the islands of Dominica, Montserrat, and St. Lucia. Dominica leads in lime production, and the exportation of lime juice, calcium citrate, and the essential oil of limes from this island is summarized in Table 111, which is taken from statistics supplied by Dr. Watts.1 TABLE111-AVERAGE
5-Year Period 1895-1 899 1900-1904 1905-1909 1910-1914 1915-1919
ANNUAL
Raw Lime Juice Gal. 127,960 249,849 208,263 348,108 600,720
EXPORTATION OF LIME PRODUCTS
DOMINICA Concentrated Lime Juice
Gal.
Citrate of Calcium Cwt.
58,486 90,295 124,643 148,571 154,185
1816 4995 2718
.... ....
FROM
Oil of Limes Gal. 2707 3983 4761 6166 6343
Ordinarily one barrel of approximately 1200 limes yields 8 gal. of raw juice (containing about IZ 02. of citric acid per gallon) and I gal. of concentrated juice (containing about 6 lbs. of citric acid per gal.). One gallon of raw lime juice yields f commercial calcium citrate. approximately I lb. o In the ordinary crude process of concentration, the expressed lime juice, after straining to remove floating impurities, is first heated in a copper still to recover the essential oil. The juice, after settling, is boiled down over an open fire in a train of copper tayches, similar to those employed in the manufacture of sirup or muscovado. The course of the lime juice is, however, opposite t o that followed in concentrating cane juice, the strike being taken from the kettle furthest from the fire, as greater losses from decomposition of citric acid occur when the final concentration is made directly over the flame. The degree of economical concentration is from about 9 volumes to I , the loss of acid becoming considerable if a higher concentration is attempted. The final product is a thick black liquid, which after cooling is run into 54-gal. casks for shipment. The loss of citric acid by open-fire concentration varies from 6 to 16 per cent. In order to reduce the loss from destruction of citric acid, an improvement has been made by concentrating the lime juice in jacketed steam-heated pans. The loss of citric acid by this method is said to be reduced to less than 3 per cent. In some localities use is also made of wooden vats heated by steam coils. Metal coils of tinned copper or of block tin are recommended as the most suitable, as they are less subject to attack by the hot concentrated acid. It has also been found that the use of granite rollers, in place of iron, for crushing the limes, gives a brighter, purer juice. The objections to concentrated lime juice, due to destruction of acid, expense for casks, leakage, freight, etc., induced Dr. Watts2 in 1902 to discuss the manufacture of citrate of calcium. After considerable experimenting he published a process for manufacturing citrate from lime juice. As a result of this work, the manufacture and exportation of citrate of calcium was started in Dominica in 1906. In the manufacture of citrate of calcium, as observed in Dominica by the writer, the juice is removed from the crushed limes by powerful presses. The expressed juice is then heated in a still to recover the essential oil, the latter being collected from the distillate in a Florentine receiver. After removing the volatile oil, the hot juice is discharged into a settling tank to deposit albumin, pectin, and other impurities. The clear liquid, together with that obtained from the filtered settlings, is neutralized with chalk and heated nearly to boiling, which “The Development of Dominica,’’ West I n d i a n Bulletin, 16, 198. ‘“Citrate of Lime and Concentrated Lime Juice,” I b i d . , 2, 308: 7 , 331; 9, 193.
01
causes the citrate of calcium to become crystalline and to settle quickly. The clear, yellow, mother liquor is drawn off; the precipitated citrate is washed several times in hot water, and then pressed or separated in a centrifugal, after which it is dried in a current of air between 150’ and 200’ F. The moisture content of the citrate should be reduced below IO per cent, as otherwise there is danger of destructive fermentation. The commercial citrate of calcium thus prepared contains about 65 per cent citric acid. The losses of citric acid by this process are reduced to about 2 per cent. The expense for chalk and the cost of drying nullify, however, certain advantages which the citrate industry has over concentrated lime juice, and large quantities of the latter still continue to be manufactured. The lime juice and calcium citrate manufactured in the West Indies are exported to the United States and Great Britain, where they are used for manufacturing citric acid for calico printing, for making beverages and medicinal preparations, and for various other purposes. ESSENTIAL OILS
LIiwEs-The principal essential oil manufactured in the British West Indies is essence of limes, which is prepared in two forms, the attar of limes or hand-pressed oil, and the distilled oil, which is a by-product in the manufacture of concentrated lime juice or calcium citrate. The attar of lines, which is the more fragrant and valuable, is removed from the fruit by an implement called from its French name an 6cueZle (meaning porringer). The latter consists of a shallow copper dish with blunt projections on the inner surface and with a hollow receptacle in the handle a t the bottom. The limes are rapidly rotated by hand across the projections, the essential oil escaping from the ruptured cells of the skin and running down into the receptacle. An expert native woman can extract over 30 02. of oil a day by this process. The oil, after pouring from the receptacle of the Ccuelle, is separated from the underlying watery fluid and filtered to remove cellular matter and other impurities. A barrel of limes yields from 3 to 5 02. of attar by the Ccuelle process, while the juice from a barrel of limes will yield from 4 to 6 oz. of the distilled oil. Analyses of West Indian hand-pressed and distilled oils, made in the Antigua laboratory by Tempany and Greenhatgh,’ showed the following results: ESSENCE OF
TABLEIV-PROPERTIES OF WEST INDIANLIME OIW HAND-PRESSED On. DISTILLEDOIL (Antigua, Montserrat, Dominica) (Dominica) 0.8659-0. 8859p 0.8540-0.8858 Specific gravity, 30°0C.. Angular.rotation, 31 , 100 mm. tube . . . . . . . . . . . . f31.38’4-33.43’ +33.09’+34.89’ Refractive index at 32’ C. 1.47891.4836 1.47021.4713 Citral, per cent. . . . . . . . 2.2 6.6 1.2 2.0 Acid number .. 1.352.8 0.761.3
.
.
..... . . . . .
The distilled oil is distinguished chemically from the handpressed oil by its lower percentage of citral, this aldehyde being partially destroyed during the boiling of the acid lime juice. BAY oIL-The distillation of bay oil from the leaves of the West Indian bay tree (Pimenta acris) is an industry of some importance in several of the West Indian islands. One of the earliest studies upon the production and chemical composition of bay oil was made by Watts and Tempany2 in the Antigua laboratory in 1910. Later experiments have been conducted in the island of Montserrat to determine whether it might not be more profitable to obtain bay oil from carefully selected and cultivated stock rather than from the wild native trees scattered through the woods. The results by Tempany and Robsona in Table V show, in fact, a wide difference in the yield and character of the oil from different trees. 1 “Notes on Expressed and Distilled West Indian Lime Oils,” Wesf I n d i a n Bulletin, 18, 498. 2 W e s t I n d i a n Bulletin, 9, 271. 8 “Bay Oil and the Cultivation of the Bay Tree as a Crop Plant,” Ibid.. 16, 176.
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TABLEV-YIELDS AND PROPERTIES OF BAY OIL Yield of Oil per 100 Lbs. Phenol Tree Green Leaves Content Specific No. Fluid Ounces Gravity Per cent 1 12.6 0,9822 at 29.5’ 65 1.0051 at 30’ 73 2 6.2 0.9610 at 29.5O 67 3 18.4 0.9850 at 2 9 . 5 : 71 4 17.3 5 24.7 0.9890 at 2 9 . 5 68 6 19.2 0.9814 a t 29’ 72
FROM
DIFFERENT TREES
Rotation in 100 Mm. Tube - 1 . 6 0 a t 2s’
........
-1.35 -2.05 -1.49
at 29’ a t 29O a t 28’
....... .
Refractive Index 1.5155 1.5187 1.5121 1.5163 1.5161 1.5152
According to these results the selection of seed for planting purposes, on the basis of yield and quality of oil, has a promising outlook. Owing to the complex composition of bay oil the haphazard methods of distillation practiced by the natives may lead to products of widely different character. The first fraction obtained by steam distillation of the leaves consists mostly of the lighter more volatile constituents, myrcene and phellandrene, which float upon the waste water in the receiver. As distillation proceeds, mixtures of oils come over that have the same density as water, and from which unaided they separate with difficulty, The later fractions consist mostly of eugenol, with small amounts of chavicol and other phenols, which, being heavier than water, settle t o the bottom of the receiver. The lighter oils in rising and the heavier oils in sinking dissolve and carry with them the portions in aqueous suspension. The mixture of the surface and bottom fractions, when distillation is complete, constitutes the normal bay oil of commerce. Should the receiver be changed a t the wrong time, the separation of the oil suspended in the waste water may not be perfect. The losses from this cause and from incomplete distillation not only diminish the yield but give rise to products of abnormal composition.
HEADQUARTERS OF IMPERIAL DEPARTMENT OF AGRICULTURE, BARBADGS, BRITISH W E S T INDIES
Experiments conducted by Dr. Tempany in the Antigua laboratory upon the changes in bay oil during storage show that the phenol content remains unchanged but that the specific gravity tends to rise considerably. The latter fact is explained by the polymerization of the myrcene, a reaction that proceeds more rapidly in the air, For this reason it is important that vessels used for containing bay oil should be tightly closed. TnYMok-At the time of the writer’s visit to the Antigua laboratory in 1919,considerable attention was being given by the acting government chemist, A. E. Collens, to the possibility of producing thymol’ from horse mint (Monarda punctata) and ajowan seed (Carum coptkum). Air-dried ajowan seed grown in Montserrat gave on distillation a yield of 3 per cent of an oil, which yielded a recovery of 43.5 per cent thymol crystals. “Notes on Thymol Content of Horse Mint and Ajowan Seed,” West Indian Bulletin, 17, 50. 1
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The calculated yield per acre was about 35 lbs. of ajowan oil, which, on a basis of 40 per cent recovery, would indicate a yield of 14 lbs. of thymol per acre. This a t present prices of the drug was considered profitable. The field and laboratory researches of the Imperial Department of Agriculture all indicate that the essential oil industry in the British West Indies has a most promising future.’ RUBBER
While the exportation of rubber from the British West Indies has not attained a leading economic importance, a large amount of investigation has been conducted by the Imperial Department of Agriculture concerning the adaptability of the various rubberproducing trees to the climatic conditions of the different islands. I n localities which have an evenly distributed rainfall of over 75 in. per year and a minimum temperature of not less than 65’ F., such as obtain in parts of Trinidad, Dominica, and Tobago, the Para rubber tree (Nevea brasilieflsis) thrives well, giving on properly cultivated plantations an average yield of 200 lbs. of rubber per acre. The Castilloa rubber tree grows better in districts with a moderate rainfall, but the yield of rubber per acre is much less than with Hevea. With the latter tree there is a steady flow of latex nearly all the year, while with Castilloa there is but little wound response and the trees must be tapped a t frequent intervals. The problems of tapping the Castilloa and dealing with its latex give difficulty and have not been perfectly solved. Probably over three-fourths of the plantation rubber made in the British West Indies is coagulated from the latex by means of acetic acid; lime juice is also extensively employed. According to Collens,2the cheapest and most efficient coagulating agent is a 5 per cent solution of sulfuric acid, in the proportion of I O drops to IOO cc. of latex. The rubber coagulated by this means was found to be of excellent quality and showed no signs of deterioration. In the process employed on plantations, the clotted cream, which rises to the surface of the coagulated latex, is gently washed, pressed, and then allowed to dry for a day. The “biscuits’’ of rubber thus prepared are then smoked for 3 or 4 days until they become transparent, during which interval they take on an amber color and acquire a characteristic smoky smell. The chief obstacle to the development of plantation rubber in the British West Indies is the scarcity of cheap labor; for this reason it is doubtful if the industry there will ever achieve the same degree of success as it has gained in Ceylon and the Malay States. Limitations of space prevent the description of other tropical industries such as those of the starches, vegetable oils, tanning materials, dyewoods, and copra, in which there is much of chemical interest both general and special. The extensive chemical investigations of the Antigua laboratory upon water supplies, soils, mineral deposits, and matters pertaining to the public health, as well as the important researches of Dr. Watts and Dr. Tempany in improving methods of analysis, must also be passed over in order that a few words may be said about the development and future of scientific research in the British West Indies. THE WORK OF SIR FRANCIS WATTS,
The early work of the Antigua laboratory, when Dr. Watts assumed charge in 1889, was begun in great isolation and under enormous difficulties. The laboratory appliances were meager, there was no gas, the library consisted of only a few general works and there was no consulting staff of scientific eo-workers; yet this lack of equipment, denoting as it did the complete 1 For the almost unlimited possibilities in this field see article by J. H. Hart, “Preparation of Essential Oils in the West Indies,” West Indian Bulletin, 3, 171. 9 “Rubber Experiments in Trinidad and Tobago,” I b i d . , 13, 219.
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any predetermined governmental policies, left the laboratory free to develop along natural lines and to take up the industrial and agricultural problems of most immediate and pressing importance. The great benefit of the laboratory was quickly felt and the scope of its work was widened when,
SIRFRANCIS WATTS,K.C.M.G., D . S C . AGRICULTURE FOR THE
IMPERIAL COMMISSIONER OF
W E S T INDIES
with the establishment of the Imperial Department of Agriculture for the West Indies in 1898,the local Antigua laboratory became a federal institution, with its field enlarged to comprise St. Kitts, Nevis, Montserrat, and the Virgin Islands. Immediately preceding this, Dr. Watts occupied for about a year the position of chemist to the government of Jamaica, but relinquished this post after the creation of the Imperial Department, to accept in 1899the appointment of government chemist and superintendent of agriculture for the Leeward Islands. He retained this position until January 1909,when he was appointed to his present office of Imperial Commissioner of Agriculture for the West Indies. From the beginning of his scientific career in the West Indies, Dr. Watts has maintained a close contact between the chemical laboratory and the Agricultural and Botanic Experiment Stations, and he has continued this policy of scientific cooperation in all his subsequent administrative work. The effect of this
has been most beneficial, as results were secured which could not have been accomplished had chemical, agricultural, botanical, and industrial research proceeded along separate unassociated lines. The training of young students for the varied needs of industrial life in the tropics is a subject to which the Imperial Department of Agriculture has given much attention and a considerable amount of Dr. Watt’s time in late years has been devoted to questions of education. I n addition to their usefulness as centers of research, the experiment stations and laboratories have been made t o serve as training places where young students may acquire practical first-hand knowledge of the subjects taught in the elementary and secondary schools. With the recent rapid growth which has taken place in developing the resources of the British West Indies a strong need has been felt for a central higher institution of, learning where advanced students could obtain a complete theoretical and practical training in the production of sugar, cacao, rubber, and other agricultural commodities. The new Tropical College, for which Sir Francis Watts has so long been working and which is soon to be established in the island of Trinidad, will remedy this need. Trinidad is an ideal location for the new institution, for not only is it conveniently situated with reference to the colonies in t h e West Indies and British Guiana, but with its varied industries of sugar, cacao, rubber, limes, and copra, as well as of asphalt and petroleum, it offers the student almost unlimited natural facilities for study and research. This college will be of much benefit to the Empire as a whole, as well as to the colonies most immediately concerned, for up to the present time the graduates of English universities who take up scientific work in the tropics have lacked facilities for acquainting themselves with the requirements of their new duties. The committee who have the matter in charge regard it as desirable that an intimate relationship should exist between the Tropical College and the Imperial Department of Agriculture, and have recommended t h a t the first president of the new institution should be the Imperial Commissioner of Agriculture. The wide experience of Sir Francis Watts in the agricultural, industrial, and educational life of the West Indies is sufficient proof of the wisdom of this recommendation. While the administrative duties of Sir Francis have obliged him t o withdraw from active work in the laboratory, his original interest in chemistry has continued unabated, and it is safe to predict that under his leadership chemical research, as a means of developing the industrial and agricultural resources of the tropics, will b d an important place in the curriculum of the new college. Sir Francis Watts by visits and by correspondence has always kept in close touch with the work of his scientific confreres in the United States, as well as in other parts of the world. He has been a visitor a t the Chemists’ Club in New York, and those who have met him there recall with pleasure his charming cordial personality. His fellow members of the AMERICAN CHEMICAC SOCIETY not only congratulate him for his enduring accomplishments but extend to him their best wishes for long (years of helpful activity t o come.
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RESEARCH PROBLEMS IN COLLOID CHEMISTRY
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By Wilder D. Bancroft CORNELL UNIVERSITY, ITHACA, N. Y Received November 5 , 1920
The following list of problems was compiled a t the request of Prof. H. N. Holmes, Chairman of the Committee on the Chemistry of Colloids of the Division of Chemistry and Chemical Technology of the National Research Council. I have received
valuable assistance in preparing this list from Messrs. Holmes and Weiser. The arrangement is somewhat arbitrary because almost any one of the problems could have been entered under a t least two
