April, 1927
INDUSTRIAL A N D ENGINEERING CHEMISTRY
t o their lower vapor pressures. The low points on the xylene curve occurred after the apparatus had stood overnight. The first determination each morning was low while the second jumped back to something like a “normal” value. This again suggests an activation period wherein the surfaces were being swept free before the adsorption of the vapor could take place. The tenacity with which water vapor is held is rkmarkable. During the time when the efficiency of adsorption was 100 per cent, the weight of the phosphorus pentoxide tube remained constant, showing that during this period the amount of vapor escaping adsorption in the glaucosil was negligible. The adsorption is reversible, as shown by the fact that the U-tube containing the glaucosil, after being run, could be brought back to its original weight by re-evacuating a t 200250’ C. Since the adsorption rate was several times as great for benzene and carbon tetrachloride as for xylene and water, time-efficiency curves differ widely with respect to the time axis. If the efficiency is plotted against weight of vapor passed per gram of adsorbent (Figure 6), the curves fall near .each other and show the same general characteristics. An initial high efficiency following the first low values is soon followed by a sharp drop to values very much lower. The .curve then flattens out and approaches zero efficiency quite ~slowly.
469
It has been suggested that this slow approach to zero efficiency might be due to spray carried along mechanically and that the “periodicity” might also be explainable on this basis. The use of the glass-wool trap would appear to make it exceedingly improbable that an appreciable amount of spray was carried over into the glaucosil. Comparison with Other Adsorbents KOdefinite comparison with other material has yet been made at this laboratory. It is interesting, however, to compare the saturation values with those obtained by Munro and Johnson4 with aluminum oxide and by Patrick and Opdycke5 on silica-gel. Saturated or nearly saturated vapors were used in each case. Table I gives a comparison of the three adsorbents. T a b l e I-Relative
Adsorptive Capacity of Glaucosil, A l u m i n u m Oxide, a n d Silica Gel ~
ADSORBENT
c. Glaucosil Aluminum oxide Silica-gel 4 6
25 20 30
~
_
_
_
_
_
_
_
ADSORBED
TEMPERATURE Benzene
Carbon tetrachloride
Per cent 40.5 16.0 24.6
P e r cent 61.0
29 0 44.9
THISJOURSAL, 17, 88 (1925). J. P h y s . Chem., 29, 601 (1925).
Our Foreign Trade in Chemicals and Allied Products in 1926’r2 By Otto Wilson MIJNSEYBUILDING, WASHINGTON, D. C.
F THE articles grouped under the term “chemicals
0
and allied products,” imports into this country in 1926 fell off slightly in value as compared with the year before, while exports registered a substantial gain. I n the trade in pure chemicals, howeyer, both the incoming and the outgoing traffic increased. The balance of trade in the products of chemical manufacture is still adverse, the excess of imports over exports last year being nearly $10,000,000. But that amount is much smaller than the normal excess before the war. Foreign Trade of U n i t e d S t a t e s in C h e m i c a l s a n d Allied Products” V- n A R IMPORTS EXPORTS BALANCE OF TR.4DE $ 80,934,000 $-37,037,000 $ 87,971,000 Average 1909-14b 176,733,000 +58,449,000 118,284,000 Average1919-23 104,735,000 15,296,000 1924 120,031,000 1925 13P,340,000 116,345,000 --21,995,000 1926 134,735,000 124,836,000 9,890,000 Figures for 1924 and 1925 differ somewhat from previously published figures for these years because of slight changes in classification in government statistics. b Fiscal years.
-
(1
For the most part the year’s trade in the various classes of commodities showed no wide variations from that of 1925. I n a number of lines there was evidence of lower prices in the decreased valuations, particularly in imports. The most striking decline was in the importation of Chilean nitrates, which were almost $10,000,000 less than in 1925, a difference much more than sufficient to account for the drop in the total for the whole group. The advance in exports is a testimonial to the healthy growth of our chemical industries, and is a continuation of a tendency strongly marked since the war. 1
2
Received February 19, 1927. All 1926 figures are preliminary
I n its published statistics the Government includes the returns for the above sub-groups in the general class “Chemicals and Allied Products.” Aside from these there are a number of commodities, such as gums and oils, included in other groups. Details of the import and export trade in the more important articles under the above sub-groups and other articles of interest to the chemical industry are given herewith. U. S. Trade i n C h e m i c a l s a n d Products by Chief Groups IMPORTS EXPORTS Chemicals Pigments, paints, and varnishes Fertilizer and materials Explosives, fuses, etc. Soap and toilet preparations
1925 1926 $48,794,000 $53,911,000
1925 1926 $59,726,000 365,248,000
3,235,000
3,859,000
18,510,000
18,887,000
78,072,000
69,249,000
17,299,000
19,672,000
1,104,000
1,165,000
4,691,000
4,223,000
7,135,000
6,551.000
16,119,000
16,806,000
CHEMICALS AND ALLIED PRODUCTS
Chemicals
COAL-TAR PRoDucTs-Imports of coal-tar chemicals were slightly less in 1926 than in the year before. Foreign Trade in Coal-Tar Products IMPORTS
Crudes Intermediates Finished Droducts
TOTAL
EXPORTS
1925 1926 $12,026,000 813,072,000 775,000 1,098,000 5.958.000 7.533.000
16 2,716,000 $ 7,060,000
$20,661,000
$10,761,000 $14,093,000
$19,805,000
1925
471,000 7,574,000
____
1926
339,000 6,694,000
The small decrease in imports was due chiefly t o a falling off in the trade in one group of articles, finished colors, dyes,
_
_
470
INDUSTRIAL AND ENGINEERING CHEMISTRY
stains, etc. These registered 4,973,000 pounds in 1926 as against 5,785,000 in 1925, the value falling from 87,166,000 to $5,601,000. The decrease occurred very largely in our purchases from Germany, the principal country supplying us with these goods, these purchases being reduced 25 per cent. Switzerland, second in the trade, also sent smaller quantities, as did Italy. But trade with France and the United Kingdom showed a gain. Among the crudes, creosote oil imports advanced from 84,869,000 gallons in 1925 to 87,519,000 gallons last year and pyridine shipments were about the same in the two years. Acids showed a 50 per cent gain, but a drop in other intermediates brought the total down. I n the export trade the 30 per cent increase was due almost entirely to a big gain in shipments of benzene. I n 1926 these totaled 143,528,000pounds having a value of $5,513,000, which compared with 58,890,000 pounds valued at $1,748,000 in the year before. Three countries, France, Germany, and the United Kingdom took practically the whole amount. I n 1925 the United Kingdom was the biggest buyer, with France second, Germany not appearing in the trade a t all. That country, however, began buying very heavily in July of last year and in the following six months ran her purchases to 60,180,000 pounds (the year’s total), which compared with 56,000,000 pounds for the United Kingdom and 14,600,000 pounds for France. This increase in volume of total trade in benzene was marked by an advance in prices which raised the average export valuation from 2.9 cents to 3.8 cents per pound. In the export trade in intermediates aniline oil and salts fell off more than one-half. Outward-bound shipments of finished colors, dyes, and stains remained a t about the same level as in 1925, last year’s total of 25,812,000 pounds comparing with 25,800,000 pounds in the previous year. But the total value fell off about 11 per cent. MEDICINALS AXD PHARMACEUTICALS-In the imports under this heading the 1926 trade showed little change from that of the year before, the total value, $5,891,000, being about 3 per cent higher. The big item in this group is menthol, which made a material gain, our purchases rising from 294,000 pounds valued a t $2,599,000 in 1926 to 459,000 pounds valued a t $2,842,000 in 1926. -4much lower range of prices was evident from the drop in average valuation of imports from $8.84 in 1925 to $6.19 last year. Japan continued to supply about nine-tenths of the total imports. Trade in quinine sulfate and other cinchona derivatives fell off nearly 20 per cent in value ($1,082,000 as compared with $1,322,000in 1925), although the total amount, 2,929,000 ounces, was not far below that of 1925. Imports of antitoxins, serums, vaccines, etc., almost vanished, being valued a t only $3400. Exports of these articles, on the other hand, increased materially, our total sales to foreign countries being valued a t $1,439,000, 15 per cent more than in the year before. As usual this was a widely scattered trade, with the Latin countries on both sides of the Atlantic being the biggest buyers, I n Europe, Spain, Portugal, and the United Kingdom regularly take large quantities of these articles, and on this side Mexico, Canada, Cuba, Argentina, and Peru are our best customers. Exports of cinchona salts were only about one-half as large last year as in 1925. The great traffic under the head of medicinals, that in proprietary medicines, showed little change in 1926 from the previous year. These compounds comprise practically all of the articles listed as “Other Medicinals and Pharmaceuticals,’’ which totaled in value $17,509,000 in 1926 as against $17,637,000 in 1925. This trade is well established in all parts of the world. The United Kingdom is the leading single buyer, taking more than $3,000,000 worth a year, but the bulk of these goods
Vol. 19, x o . 4
goes to Latin-American countries, particularly Cuba and Mexico. ACIDS .4KD ANHYDRIDES-The value Of our imports of arsenious acid or white arsenic continued to decline last year, reaching a figure of only $511,000. In the year before it was twice that amount and in 1924 three times as much. This decrease has been due very largely to heavy price declines. Tge total of last year’s shipments, 15,418,000pounds, was some 17 per cent below that of 1925 and 13 per cent less than that of 1924. I n two years the value of these imports has decreased from an average of 8.9 cents per pound to 3.3 cents. The large 1925 trade with Mexico continued last year and that country sent us some three-fourths of our requirements, Japan and Canada being the other important sources. Sulfuric acid imports continued to grow steadily and last year were nearly four times as heavy as two years ago. As compared with 1925, the 1926 shipments of 56,937,000 pounds were 50 per cent larger. Tartaric acid imports, 1,565,000 pounds valued a t $330,000, were less than half those of the year before. The decrease occurred particularly in the trade with Italy, the chief country of supply. Citric acid imports were only about one-fifth as large as in the year before, the amount being 138,000 pounds, and oxalic acid, 1,567,000 pounds, was 40 per cent less. But formic acid, 2,316,000 pounds, made a 50 per cent gain. Exports of acids are much below imports. The largest export item is sulfuric acid, which goes entirely to Canada. The 9,224,000 pounds shipped in 1926 represented a 20 per cent gain. Boric acid, 1,416,000 pounds, doubled the 1925 trade, but acetic acid, 463,000 pounds, was nearly a third smaller. ~ 4 ~ c o ~ o ~ s - I m p o roft s methanol during the first eleven months of the year maintained themselves somewhat above the level of the previous year. I n December came a great rush of shipments because of the increase in duty effective December 27, and these sent the year’s total 50 per cent higher than for 1925. Imports in the first eleven months were 553,000 gallons valued a t $252,000, and in December 202,000 gallons valued a t $93,000, making the 1926 total imports 755,000 gallons valued a t $345,000. These compared with 508,000 gallons valued a t $231,000 in 1925. In both years all imports came from Germany. The import valuation in 1926, 45.7 cents per gallon, was practically the same as that of the year before. The effect of the competition of German synthetic methanol on our export trade has been marked, but complete returns for the year show that the displacement has not yet been so great as those interested in the trade feared it might be. Our total exports last year were in fact slightly higher than in 1925, although only about 65 per cent of the 1924 figure. EXPORTED TG: Iielgium France United Kingdom Canada
Cuba
Japan Panama Other countries
TOTAL TOTAL VALUE
Exports of Methanol 1924 1925 Gallons Gallons 52,000 40,000 79 224,000 98,ono 35,000 62,000 45,000 79,000 172.000 10R,000 34,000 140 72,860 28,921
...
641,000 $SS7,000
408,000 $321.000
1926
Gallons
..
93
89,000 20,000 71,000 155,000
zn,ooo
61,907 417,000 $312,000
Exports in the last two years have been at much lower prices than formerly, and that has doubtless helped to maintain the trade. I n 1924 the average valuation of methanol exports was $1.07, in 1925, 78 cents, and in 1926, 75 cents. Of the other alcohols the most important import was butyl alcohol, 205,000 pounds valued a t $33,000, a large decline
INDUSTRIAL A N D ENGINEERING CHEMISTRY
April, 1927
from the 2,152,000 pounds valued a t $393,000 in 1925. Fusel oil also declined, imports being 208,000 pounds as against 271,000 pounds in the year before. OTHER CHEMIcALS-Imports and exports of other chemicals of importance in the last two years were as follows: Foreign T r a d e in M i s c e l l a n e o u s Chemicals in 1925 a n d 1926 1925
Pounds
1928
Pound5
IMPORTS
,4mmonia compounds Barium compounds Calcium carbide Cobalt oxide Copper sulfate (blue vitriol) Lime: Chlorinated, or bleaching powder Citrate of Glvrerol: ?rude Refined Iodine, crude Magnesium compounds Potassium compounds: Carbonate Caustic potash Nitrate, crude, or saltpeter Bitartrate, crude, argols, 01 wine lees Chlorate and perch!orate Other Sodium cyanide Ferrocyanide (yellow prussiate) Sodium nitrite Radium salts and radioactive substances
\
23,893,000 20,112,000 14,241,000 287,000 1,805,000
25,316,000 24 477,000 21 845,000 333,000 2 5a9.000
2,100,000 3,431.000
3,767,000 3,371,000
21,292,000 246,000 24,348,000
10,880,000 t 27,t564,000 711,000 29,997,000
8,396 tons
1l,.i23,000 12,914,000 9,416 tons
24,666,000 11,834,000 12,893,000 30,212,000 1,637,000 1,971,000
2.5,625,000 13,537,000 11,772,000 31,804,000 815,000 1,927,000
7,895,000 12,287,000
169 qrains (vahie $549,000)
EXPORTS
Ammonia and compounds Aluminum siilfate Raking powder Calcium compounds: Acetate of lime Calcium carbide Chlorinated lime Copper sulfate Dextrine or British gum Formaldehyde Glycerol Petroleum jelly Disinfectants, insecticides, etc Potassium compounds Sodium compounds: Borax Caustic soda Soda ash Bichromate and chromate Silicate (water glass) Cyanide Sal soda Bicarbonate Other
4,521,000
4 1,612,000
4,026,000 22,038,000 4,8.i;1,000 27,389,000 6,139,000 22,678,000 2,799,000 1,367,000 6,482,000
1,878,000 60,005,000 4,501,000
4,310,000
li,589,000 4,534,000 20,858,000 1,799,000 22,363,000 2,387,000 768,000 :‘3,095,0no 13,190,000 3,356,000
33,888,000 100,9L~5,000 32,380,000 7,299,000 40,517,000 1,592,000 13,392,000 17,298,000 108,024,000
2h,610,000 103,295,000 39,533,000 8,52i,000 48,345,000 1,883,000 12,653,000 19,339,000 83,853,000
(a)
471
Of the chemical pigments lithopone is the most important. That and other zinc pigments totaled 18,796,000 pounds valued a t $916,000 in 1926, one-fifth more than in 1925. Czechoslovakia, Germany, the United Kingdom, and the Setherlands send us most of our imported paints, stains, and enamels, and Germany and the United Kingdom n o s t of our varnishes. Exports under this group go to all parts of the world, American paints and varnishes being favorably known in almost every civilized country. Ready-mixed paints are the big export commodity. Canada is the largest buyer of our mineral-earth pigments, and South Africa is second. The United Kingdom is the leading buyer of chemical pigments, chief of which is carbon black. Fertilizers and Fertilizer Materials
The effects on our foreign trade of our domestic production of synthetic nitrogen salts were very noticeable in 1926. Imports of Chilean nitrates fell off almost 20 per cent, sulfate of ammonia imports dropped 65 per cent, and exports of sulfate of ammonia increased by 40 per cent. Chilean nitrate imports, 914,000 tons, compared with 1,112,000 tons in 1925 and 987,000 tons in 1924. Prices were only slightly reduced, the average valuation being $46.79 as compared with $47.23 in 1925. Germany’s shipments of sulfate of ammonia to this country fell from 19,600 tons in 1925 to 5400 tons last year. Kearly all the imports came in the early part of the year, and in the last six months the trade almost disappeared. Imports of bone phosphates, totaling 46,700 tons valued a t $1,380,000, almost doubled those of 1925. All classes of potash imports showed a gain except manure salts. Imports of Potash 1925 Tons Value Chloride, crude (muriate) 161,000 $5,194,000 Sulfate, crude 69,000 2,686,000 Kainite 183,000 1,173,000 Manure salts 384,000 3,677,000 Other potash-bearing substances 24,000 321,000
1926
Tons
Value
199,000 70,000 182,000 316,000
56,196,000 2,823,000 1,225,000 3,391,000
48,000
498,000
Of the muriate, kainite, and manure salts about 30 per cent came from France, and of the sulfate about 6 per cent. Germany sent 60 to 66 per cent of the first three salts and 90 per cent of the sulfate. I n the export trade in sulfate of ammonia, which totaled Pigments, Paints, and Varnishes 174,000 tons valued a t $9,456,000, our two best customers I n both the outgoing and the incoming trade the increases substantially increased their purchases last year. These of 1925 continued last year, although the gains were not so are the Dutch East Indies and Japan, which between them large. Our purchases of these goods from foreign countries take two-thirds of our exports. Exports of phosphate rock totaled 749,000 tons valued were nearly 20 per cent higher in value than in 1925, but exa t $4,440,000 in 1926 as against 870,000 tons valued a t ports gained only about 2 per cent. $5,678,000 in 1925. Superphosphates, 64,000 tons, were Trade in P i g m e n t s , Paints, and V a r n i s h e s also slightly less. IMPORTS EXPORTS Explosives, Fuses, Etc. 192#5 1926 1925 1926 Mineral-earth pigments $1,210,000 Sl,538,000 S 903,000 S 1,006,000 Under this heading the largest import article is firecrackers, Chemical pigments 1,458,000 1,502,000 7,678,000 7,983,000 Paints, stains. and 1-alued a t $795,000 last year, about 6 per cent under 1925. enamels 519,000 742,000 7,904,000 7,857,000 Varnishes 2,040,000 all of them come from China. ~ 51,000 ~ 77,000 - 2,025,000 _ _ Practically _ Exports are several times as large as imports, the chief TOTAL $3,235,000 S3,869,000 818,510,000 SlS,S86,000 outgoing commodity being dynamite. Kearly all of it goes I n the import trade the largest item under “-Mineral-earth to Canada and to Latin--4merican countries. The total last pigments” was iron oxide and hydroxide pigments, amount- year, 16,221,000 pounds valued a t $2,331,000, was about ing to 27,987,000 pounds valued a t $667,000. These prac- 5 per cent less than in 1925. Smokeless powder is the second tically all come from four countries, Spain. the United largest export, Mexico, Greece, and Canada taking most of Kingdom, Canada, and Germany. Spain sent about two- the $453,000 exported in 1926. thirds of the total last year. Ochers and siennas, largely Soaps and Toilet Preparations from France, gained 3 or 4 per cent in volume, which totaled 20,846,000 pounds, but 40 per cent in value, which reached Perfumery, bay rum, and toilet water were purchased $390,000. abroad last year to the value of $2,138,000, practically the Total sodium compounds Washing powder a n d fluid Blackings and polishes .3 N o t stated separately.
356,345,000 4,516,000 10,673,000
-~
34ti,038,000 4,935,000 9,178,000
4 72
INDUSTRIAL AA’D ENGINEERING CHElMIsTR Y
same as in the year before. I n the trade in perfume materials last year the growth that has been in evidence for some time was checked and total imports fell off in value as compared with 1925. For the last five years the value of these imports has been as follows: 1922, $769,000; 1923, $2,470,000; 1924, $2,905,000; 1925, 83,388,000; 1926, $2,799,000. The trade is very largely with France, although Switzerland, Germany, and the Netherlands send considerable quantities each year. Imports of toilet soap, which totaled $409,000 last year, were largely from France, as usual, with the United Kingdom a good second. Shipments of castile soap, $246,000 in value, came chiefly from Italy, followed by Spain and France. I n the export trade dental creams and other dentifrices continued to enlarge their widespread markets abroad, sales being valued a t $3,381,000, as compared with $3,211,000 in 1925. The United Kingdom and its dependencies and associated dominions take more than half of these exports, the remainder finding their way to practically every other country of the world. The total value of this trade was surpassed last year by that of laundry soap, exports of which were valued a t $4,120,000. As in previous years the biggest buyers were Mexico, Canada, Cuba, Haiti, the Dominican Republic, and the Philippines. Talcum and other toilet powders were sent abroad in slightly smaller amounts, the total value $1,727,000, being about 8 per cent under that of 1925. MATERIALS RELATED TO CHEMICAL INDUSTRIES
The following groups of commodities are more or less directly related to chemical industries, although in the foreign trade statistics they are placed in other classes than “Chemicals and Related Products.”
I m p o r t s of Essential a n d Distilled Oils
1925
Pounds
Cassia and cinnamon (5) Geranium 203,000 Otto of roses 56,80002. Bergamot 116,000 Citronella and lemon grass 1,322,000 Lavender and spike lavender 183,000 Lemon 488,000 Orange 228,000 Sandalwood 22,000 All other 3,019,000 a
The steadily increasing drain on our mineral oil resources, as shown in the export statistics, was marked in 1926. Both crude petroleum and the various refined oils were sold abroad in much larger quantities, the only exception being lubricating oils. Exports of Mineral Oil8
1925 Gallons Value 551,257,000 $ 24,275,000
registered exports of 96,900,000 pounds valued a t $11,785,000 for the year, this comparing with 91,972,000 pounds valued at $11,814,000 in 1925. Germany and the United Kingdom were as usual the chief purchasers of lard, the total of which, 698,970,000 pounds, was about 2 per cent higher than in the year before while the value, $108,600,000, was 8 per cent less. Exports of neutral lard were somewhat smaller both in amount and value than in 1925, and lard compounds decreased about 30 per cent. In the import trade vegetable edible oils, consisting almost wholly of olive oil, decreased about 13 per cent, from 90,490,000 pounds t o 78,592,000 pounds. Italy furnishes about two-thirds of these imports. Of the inedible vegetable oils much the largest in the import trade was coconut oil from the Philippines, 245,000,000 pounds valued a t $22,088,000, about 6 per cent more than in 1925. Chinese wood or nut oil decreased about 18 per cent, the 1926 shipments amounting to 83,000,000 pounds. Palm oil, 130,747,000 pounds, fell off somewhat from 1925 but palm kernel oil, 74,980,000 pounds, was 40 per cent more. Linseed oil imports were only 861 pounds in 1926. In the year before they were 1,643,000 pounds.
TOTAL
Mineral Oils
1926 Gallons Value 647,054,000$ 28,496,000
Petroleum crude Gasoline. naDhtha and o&ef light 1,286,788,000 197,492,000 1,786,648,000 263,557,000 products 885,136,000 84,700,000 912,906,000 99,184,000 Illuminating oil Gas and fuel oil 1,365,359,000 49,040,000 1,449,688,000 45 354 000 403,052,000 91,063,000 389,160,000 86:822:000 Luhricating oil ~
The gain in crude petroleum exports was due t o heavily increased shipments to Canada, 545,278,000 gallons, 50 per cent more than in 1925. The increase in gasoline sales was due to no one country but was spread generally over the trade. The United Kingdom took 614,400,000 gallons in 1926 as against 345,950,000 gallons in 1925. Besides the exports of gas and fuel oils as given above, 46,662,000 barrels were loaded as fuel or bunker oil on vessels engaged in foreign trade as against 46,827,000 barrels in 1925. Vegetable, Animal, and Essential Oils
There was a large drop last year in exports of cottonseed oil, the total of which for 1926 was 40,900,000 pounds, valued at $4,090,000, as against 62,400,000 pounds valued a t $6,517,000 in 1925. The decrease was general, applying to all the leading countries in the trade. Canada is much the largest buyer, taking more than half the total. Exports of edible animal oils were somewhat larger in amount, although they fell off in value. Oleo oil, going chiefly to Germany, the Xetherlands, and the United Kingdom,
Vol. 19, No. 4
....
1926 Value (a)
$ 808,000
293,000 403,000
Pounds 322,000 222,000 34,00002. 75,900
Value $ 474,000
526,000 364,000 418.000
1,069,000
1,320,000
745,000
598,000 447,000 499,000 103,000 2,135,000
198,000 508,000 209,000 4,600 3,132,000
.509,000 974,000 506,000 12,600 2,044,400
6,345,000
.. . .
6,573,000
Not separately stated.
Exports of essential and distilled oils were about the same in value as in 1925. The total was $1,695,000. There was a sharp drop in the value of peppermint oil from $776,000 to $571,000, although the amount, 67,800 pounds, was practically the same as in 1925. Dyeing and Tanning Materials Quebracho extract imports fell off slightly in 1926, the total of 102,162,000 pounds being less by nearly 10 per cent than imports in the year before. Quebracho wood, however, increased from 22,700 tons valued a t $387,000 to 32,000 tons valued a t $510,000. Logwood, the second most valuable commodity of this class, was valued a t $510,000 in 1926 as against $403,000 in 1925. The total value of imports of dyeing and tanning materials fell from $8,190,000 in 1925 to $7,890,000 last year. I n the export trade there was also a decrease, $1,839,000 in 1926 comparing with $1,939,000 in 1925. Rubber Imports of rubber continued to climb higher in 1926, amounting to 925,878,000 pounds valued a t $505,818,000, as compared with 888,478,000 pounds valued at $429,705,000 in 1925. The average valuation of last year’s imports was about 55 cents as compared with 48 cents in 1925 and 24 cents in 1924. Naval Stores, Gums, and Resins Total exports of articles under this heading were much larger than in 1925, being valued at $36,865,000, as compared with $31,810,000. The gain was in exports of rosin, $24,633,000, a third larger than in 1925, although the quantity, 1,094,000 barrels, represented a small decrease. Germany
IXDUSTRIAL AND ENGIiVEERING CHEMISTRY
April, 1927
and the United Kingdom together take about one-half the exports. The average valuation of exports in 1926 was $22.51 per barrel, as against $16.11 in 1925. Spirits of turpentine were exported to the extent of 11,587,000 gallons, practically the same as in the year before. The value was $10,636,000, about 6 per cent less than in 1925. Imports of gums, resins, and balsams continued to increase in 1926, amounting to a value of $34,048,000 against 330,751,000 in 1925. The largest single item in point of value was shellac, the total quantity of which was 31,296.000 pounds,
473
50 per cent more than in 1925. The value, however, totaling $10,515,000, was but little higher than in the year before. Both dammar, 15,156,000 pounds, and kauri, 5,456,000 pounds, were well above the 1925 imports. Synthetic camphor imports increased from 1,835,000 pounds valued a t $921,000 in 1925 to 2,944,000 pounds valued a t 81,558,000 in 1926, all from Germany. Natural crude camphor imports were 2,019,000 pounds, valued a t Sl,l58,000, somewhat less than in 1926, and refined 1,170,000 pounds valued at $783,000, also a decrease.
Commercial Gelatins‘ Their Jelly Strength, Gold Number, and Hydrogen-Ion Concentration By Paul Serex and M. W. Goodwin MASSACHUSETTS AGRICULTURAL COLLEGE,
D
.4MHERSf,
MASS.
*THIS J O C R X A L , 15, 699 (1921).
distilled water mere heated in a 400-500-cc. Pyrex beaker. During the heating, 2.5 cc. of a AuCls. HCl. 3Hz0 solution (6 grams per liter) and 3.5 cc. of an 0.18 N potassium carbonate solution were added. The resultant solution was then heated to the boiling point, and was constantly stirred to insure uniformity. 4 s soon as the solution started to boil, one or two drops of a 40 per cent solution of formaldehyde were added, the solution being stirred rapidly all this time. Upon the appearance of a red coloration the solution was removed from the heater and allowed t o cool. A sufficient quantity of this red gold sol was prepared, and thoroughly mixed, so that the necessary number of determinations might be made without further preparation of new samples. Gold numbers vary with the nature and concentration of gold sol and the protective colloid. The values are comparative only, the hydrophile with the lower gold number being the better protective colloid. The gold number, which represents the relative protective power, is defined by Zsigmondy5 as the number of milligrams of a protective colloid that just fails to protect 10 cc. of a colloidal gold sol against precipitation by 1 cc. of a 10 per cent sodium chloride solution. Determination of Gold Number One gram of gelatin was added to 500 cc. of conductivity water and heated to 75” C. in 20 minutes. It was allowed to cool to about 38” C. and then aged a t a constant temperture for exactly 24 hours. From this solution the required dilutions were prepared. Then to absolutely clean glass tubes was added 1 cc. of the various dilutions-i. e., 0.1, 0.01, and 0.001 mg., etc.-and to each of these were added 10 cc. of the gold hydrosol. Each tube was thoroughly shaken and allowed to stand 3 minutes. After this interval 1 CC. of the sodium chloride solution was added, shaken thoroughly, and allowed to stand 2 minutes before observations were made. By means of intermediate dilutions the maximum amount of the gelatin which just failed to protect the gold hydrosol from precipitation was readily determined. The value of this amount expressed in milligrams is the gold number of the sample of gelatin. Great care was taken to have all glassware absolutely clean, as there was only a very slight difference between the gold numbers of widely different samples of gelatin. Preparation of Gelatin Dispersions for Jelly Strength Determinations Seven-gram samples of gelatin were weighed out and placed in glass containers which had the following speci-
J. P h y r . Chem., 29, 792 (1925). J. D u i v y Sci.. 8, 500 (1925).
Zsigmondy-Spear, “Chemistry of Colloids,” p. 106, John Wiley & Sons, I n c , 1917.
URIKG recent years numerous investiqations have been carried out on the physical and chemical characteristics of gelatin. From the standpoint of the manufacturer and the consumer the important characteristics of gelatin are jelly strength, riscosity, hydrogen-ion concentration, ash content, protective power, color, clarity, odor, and purity. Since the ice cream trade has required the manufacturer to make a smoother product, the practice of adding gelatin or some other protective colloidal dispersion to the ice cream mix has become universal throughout the industry. The authors realize that the determination of the gold number and the hydrogen-ion concentration is impracticable for the majority of ice cream manufacturers, but the determination of jelly strength is practicable because it can be carried out very successfully by the non-technical worker. The object of this investigation, therefore, was to ascertain whether or not any relationship exists between the jelly strength, the gold number, and the hydrogen-ion concentration of various commercial gelatins used in the manufacture of ice cream. Elliot and Sheppard2 found very little difference in the protective action of seventeen different gelatins of all grades and methods of manufacture. They also found that any classification of gelatins according to their gold numbers was too rough and did not bear any simple relation to the properties of chief interest to the users of gelatins. Tartar and Lorak3 found that between p H values of 8 and 5 the hydrogen-ion concentration had practically no influence on the protective action; below a p H of approximately 4.7, the protective action decreased very rapidly with increase of hydrogen-ion concentration. Some time after the beginning of the present investigation, Moore, Combs, and Dahle4 published their results, from which they concluded that there was no direct relationship between gold numbers, hydrogen-ion concentration, and jelly strength. They used six different gelatins. Samples of commercial gelatins were obtained from nine of the leading gelatin manufacturers, and their high-, medium-, and low-grade gelatins were selected for this investigation. Preparation of Gold Sol
For the determination of the gold number, Zsigmondy’s red sol was prepared in the following manner: 120 cc. of re-
’ Received 3
4
January 27, 1927.
