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ances bearing the laboratory seal of approval are being sold as approved. These inspections will be made at least once a year and more often if necessary. Where proper standards are being maintained, approval certificates will be issued covering each succeeding year, and once secured, are good indefinitely unless some changes are made that require additional tests. Accomplishments to Date During the past two years the laboratory has conducted research in the preparation of safety requirements for gas ranges, space heaters, water heaters, and central househeating appliances, and also approved from test or inspection approximately 6000 gas ranges, 300 space heaters, 50 water heaters, 15 types of flexible gas tubing, and a number of central house-heating appliances. Considering that there are about 175 tests made on a gas range, 250 tests on a space heater, 200 tests on a water heater, and 150 tests on a central house-heating appliance, this demonstrates that an enormous amount of work has already been done. Research on Mixing Gases While the work of the testing laboratory is largely confined to routine testing, considerable research work has recently been done on mixing gases. This subject has become very important to every one in the gas industry. I n some localities the natural gas supply is rapidly decreasing, necessitating mixing with the natural a manufactured gas of different heating value and different specific gravity. I n other localities a large quantity of by-product coke-oven gas of low specific gravity is available, but there is not a sufficient quantity to supply the entire demand. Therefore, it is mixed with another gas, usually carbureted water gas of about the same heating value but much higher in specific gravity. The supply of oil, being somewhat doubtful, may necessitate mixing oil gas with coal or some other kind of gas as the price of oil increases. The gas industry as a whole is interested in the question of how far jt can go in varying specific gravities, or heating values, or both, and still maintain satisfactory appliance operation. It is an easy matter t o manufacture and mix
Vol. 20, No. 3
gases of different heating value and specific gravity, but the question arises as to how closely the mixing must be regulated without affecting the operation of gas appliances already in service. The laboratory is obtaining fundamental data on this subject. Although the whole investigation may not be finished for three or four years, the first phase of the work-that of finding out the effect of varying the specific gravity, the heating value remaining constant-will soon be completed. Investment At the present time the testing laboratory represents an investment of about $500,000 on the part of the gas industry, $125,000 of which was contributed by gas-company members; the remainder represents test fees that have been used partially to retire operating expenses and investments necessary on the part of appliance manufacturers to bring their equipment up to present standards. Importance of Undertaking With the hearty cooperation of every one concerned in this undertaking the testing laboratory is sure to succeed. It is founded by a great industry in the interest of better public service. It is raising the standards of construction and performance of gas-burning equipment and developing the art of appliance design. Already there are many signs of new developments, and a marked improvement can be seen in the approved ranges and space heaters being sold a t the present time. The same can be said of water heaters and central house-heating appliances, when they are added to the approved list. This will also be true of other types of appliances submitted later for tests. The gas industry appreciates the value of science in business. It realizes that it cannot with justice to the future of its business afford to shape its appliance policies after the customs and traditions of the past. The establishment of the Testing Laboratory was an epoch-making advance in the gas business and public evidence of the industry's consciousness of its moral responsibility to safeguard to the best of its ability the millions of people who are daily dependent on gas as one of the essential services of life.
Properties and Uses of an Edible Rice Cellulose' E. R. Harding MELLON INSTITUTE
A
OF IXDWSTRIAL REsCARCH, UNIVERSITY O F PITTSBURGH, PITTSBURGH,
RECENT advance in food technolow -" is the develoDment of a process of recovery of an edible celluloie from the hulls of rice and other cereals. Cellulose is a natural constituent of practically all vegetable foods and is really an essential dietary constituent. By adding bulk and roughage to the intestinal contents normal elimination is promoted and constipation largely prevented. I n the development of a new ready-to-serve breakfast food milled rice was found to be the most desirable cereal base. Because of the low cellulose content of milled rice it was decided to reenforce the roughage content of the finished cereal by additions of a pure cellulose of suitable physical form. It was found that a satisfactory pure edible cellulose could be prepared from the hull of the rice, thus making the breakfast food an all-rice product. The cellulose of the hull is first isolated in a semifibrous form by a strong soda cook. A hydration treatment then reduces it to the proper physical form for use as an edible material. 1
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Received December 24, 1927.
PA.
A large plant for the production of this new form of pure cellulose has been in operation for some time. It is located at Lake Charles, Louisiana, adjacent to the largest rice mill in the world. Rice cellulose as prepared for food roughage is a light, somewhat fluffy, fine, mealy material. It has a light cream color, but is easily bleached white if desired. It is odorless and tasteless. It has a mealy feel in the mouth, and although not intended to be eaten straight, when well moistened with saliva, can be swallowed without difficulty or irritation. Its ash content has been reduced to 1.0 per cent or less, although the original raw material contains about 18 per cent of ash that is largely insoluble silica. The washed product from the alkaline digestion may run as high as 99 per cent alpha-cellulose. I n the finished product a part of the original compound or normal celluloses has been converted to simpler hydrated celluloses; but the freedom from impurities of noncellulosic character entitles it to be called a practically pure cellulose.
INDUSTRIAL A N D EN'GINEERIA'G CHEMISTRY
March, 1928
Analyses of typical samples of rice cellulose which have been given the hydration treatment are given below: Alpha-cellulose Hydrated cellulose Copper number Ash
A 73.16 24.16 8.91 0 74
B
C
D
E
72.51 24.74 9.16 0.86
72.26 24.91 8.65 0.83
73.04 2 3 86 9 32 0 97
73.09 23.72 9.04 0.68
Rice cellulose was primarily produced to supply moistureabsorbing roughage material for a ready-to-serve breakfast food. It is also suitable for enriching the roughage content of many other foods such as bread, muffins, pan cakes, crackers, thick soups, soft cheese, sandwich spreads, confections, etc. The use of substantially pure cellulose or hydrocellulose in foods in general and in prepared cereal foods in particular is protected by patents2
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The value of edible rice cellulose when used as a dietary roughage has been proved by a comprehensive series of practical tests. Using as subjects large groups of persons in two institutions-namely, an orphanage and a home for the agedit was shown that when a rice-flake breakfast food containing a moderate percentage of purified cellulose was eaten regularly constipation was prevented or corrected in all except the most obstinate cases. There were no gastro-intestinal disturbances in these subjects. After feeding the cellulose for a long period to white rats its harmlessness was proved by autopsies on the animals, which showed no evidence of irritation to the digestive tract. 2
U. S. Patents 1,495,789and 1,547,582.
Formation and Solution of Calcium Hydroxide Crystals in Portland Cement' Jasper 0. Draffin DEPARTMENT OF THEORETICAL AND APPLIED MECHANICS. UNIVERSITY OF ILLINOIS, URBANA. ILL.
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H E S Portland cement is mixed with water it sets and finally hardens, and in so doing it liberates calcium, which later crystallizes from the solution as calcium hydroxide in the form of stout prisms and hexagonal plates. This calcium apparently comes from the di- and tricalcium silicates which hydrolyze under the action of the mixing water. During some studies on the hydration of tricalcium silicate it was observed that some of the crystals of calcium hydroxide which were formed in the solution were later dissolved in the solution from which they vrystallized, the temperature remaining the same as when they formed. The method of study was to mix some finely powdered tricalcium silicate, which contained only very small amounts of magnesium, aluminum, and iron oxides, with distilled water on a glass slide, cover it with an object glass, and cement around the edges with Canada balsam. This left the tricalcium silicate in nater which could not evaporate and from which the air was excluded. The progress of hydration on these slides was observed by means of a petrographic microscope. About 12 hours after preparation many calcium hydroxide crystals could be observed and these reached their maximum size in 2 or 3 weeks. Many of these crystals had begun to corrode or dissolve a t the end of 3 weeks, but this period was not constant; sometimes it was as early as 16 days; evidently it was related t o the period of growth of the crystals. In many slides the crystals had dissolved completely in from 5 to 6 weeks, though the outlines were clearly defined after solution. Other slides showed some crystals dissolved while near them were crystals which were unaffected. The accompanying sketches show the manner in which the corrosion takes place. It generally begins on a prism face and not on a basal plane. In searching for an explanation of the unusual action of a crystal dissolving in the solution from which it was formed, a number of possibilities were considered. One rn as a change t o calcium carbonate. This w-as eliminated because the Canada balsam excluded the air and besides there was no trace of calcium carbonate on the slide. Another possibility was that of diffusion of the saturated solution from around the crystals to other parts of the slide, leaving unsaturated solution around the crystals. This was tested by preparing 1
192s.
Received January 28, 1927.
Revised paper received January 6,
some slides with the tricalcium silicate concentrated at one side of the slide and other slides with the tricalcium silicate evenly distributed over the surface. KO difference in action could be detected from this cause. R. H. Bogue, research director of the Portland Cement Association Fellowship investigation, suggested that the soft soda-lime glass used in the slides and cover glasses might dissolve slightly and react with the calcium hydroxide in the solution. That would result in a gradual dissolution of the calcium hydroxide crystals and the reprecipitation of hydrated calcium silicate. It would account also for the skeleton outline of the crystals remaining after the completion of the reaction. $ccordingly, some quartz object slides and fused-quartz cover glasses were obtained and experiments nere carried on with these. KO solution of crystals occurred mith the quartz slides, though they were observed for 3 or 4 months. This ind i c a t e s that the corrosion and Sketch Showing Corrosion of Calcium tion of the crystals Hydroxide Crystals. Shaded Portion Shows Part Dissolved was. caused .. by the (Enlarged about 50 times) soda-lime glass slides dissolving slightly, and it is believed that this is the correct explanation. The amount of solution of the slides is extremely small, so small that it cannot be detected with a microscope after the removal of the cover glass. The acceptance of this explanation raised the question as to what would be the effect on calcium hydroxide crystals in concrete when they were in contact with soda-lime minerals such as the feldspars. Experiments were therefore made in which finely powdered albite, labradorite, and anorthite were mixed with the tricalcium silicate on quartz slides, each mixture on a separate slide, to determine whether the feldspar would dissolve and cause the solution of the calcium hydroxide crystals. The addition of the feldspars did not cause corrosion of the calcium hydroxide crystals. Apparently the soda-lime glass is more susceptible to the action of calcium hydroxide than the soda-lime minerals. Experiments with the feldspars mixed with the tricalcium silicate are being continued.
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