158 



CHEMISTRY. (INDUSTRIES.) 



the ordinary conditions of warmth and moist- 

 ure that are proper for the growth of agricult- 

 ural plants ; but it was not such as to encour- 

 age the idea of instituting a test or assay of 

 the nitrogen value of any given soil. That is 

 dependent on other conditions than chemical 

 composition, among which may be those that 

 are favorable or unfavorable to the develop- 

 ment of the organism on which nitrification 

 depends. In the experiments made with ref- 

 erence to this point, the jars were variously 

 watered with rain-water and solutions of sul- 

 phate of potash, phosphate of potash, sulphate 

 of lime, chloride of potassium, nitrate of lime, 

 and nitrate of ammonia. The results of the 

 experiments showed that, while a method of 

 assay of this kind could readily distinguish a 

 true garden-soil from a mediocre loam, it was 

 incapable of exhibiting any definite practical 

 distinction between ordinary loams. 



A. B. Griffiths has drawn the conclusion 

 from repeated experiments that ferrous sul- 

 phate is good plant-food when sparingly ap- 

 plied. A solution containing as much as one 

 fifth per cent, of it is, however, fatal to most 

 plants. A fairly large proportion of soluble 

 iron in the soil is favorable to the growth of 

 plants developing a large amount of chloro- 

 phyl. Iron is regarded by the author as 

 closely related to the production of chloro- 

 phyl, and the increased production of soluble 

 carbo-hydrate?, woody fiber, and fat in certain 

 cases, is a direct consequence of the increase 

 in chlorophyl. Nitrogen is also increased by 

 the use of ferrous sulphate, and the salt acts 

 as an antiseptic agent in the soil to prevent 

 parasitic diseases of the plant. 



Industrial Chemistry. The oils most in demand 

 and highest in price are exceedingly liable to 

 adulteration with inferior or cheaper oils ; but, 

 unfortunately, in the absence of any charac- 

 teristic test for each oil, such as we have for 

 each metal, the determination of the adulterant 

 is extremely difficult if not quite out of the ques- 

 tion. When, however, we examine an oil sup- 

 posed to be adulterated, much can be accom- 

 plished, says Mr. Oscar 0. S. Carter, in a paper 

 on the subject, by procuring a sample of per- 

 fectly pure oil and subjecting both to the same 

 tests and observing their behavior. According 

 to Prof. Bichi, of Florence, cotton-seed oil can 

 be certainly detected in olive-oil by the test of 

 a one-per-cent. solution of nitrate of silver in 

 absolute alcohol. If there be cotton-seed oil 

 present, even in the most minute quantity, the 

 mixture will begin to darken to a tint depend- 

 ing on the amount of the adulterant present. 

 Mr. Carter, applying the same test to lard-oil, 

 found that a specimen known to be pure was 

 not affected at all; while a specimen of the 

 ordinary commercial oil began to darken when 

 it had been heated for a few minutes, and final- 

 ly became quite black. The elaidin test is 

 sometimes very satisfactory, especially in de- 

 tecting a mixture of a drying and non-drying 

 oil, and in detecting adulteration of olive-oil. 



This test depends upon the fact that olein and 

 oleic acid in contact with peroxide of nitrogen 

 yield a crystalline, solid, fatty body soluble at 

 32 0., to which Boudet has given the name 

 elaidin. The nitrous vapors made by the ac- 

 tion of nitric acid on copper are passed through 

 the oil, or it may be shaken with a fresh solu- 

 tion of mercurous nitrate, which has the prop- 

 erty of retaining nitrous acid. Non- drying 

 vegetable oils and most animal fats contain 

 oleic acid. The following oils contain a high 

 percentage of olein : Olive, almond, rape, ara- 

 chis (earth-nut), castor, and the oils from lard 

 and tallow. These oils form with nitrogen 

 peroxide solid elaidin of a white or yellow 

 color, which in some cases is firm and reso- 

 nant. The drying oils, such as linseed, hemp- 

 seed, and poppy-seed oils, do not form solid 

 elaidin with nitrous vapors, but remain liquid 

 for more than two days and become slightly 

 colored. The elaidin test was applied to the 

 lard-oils. The elaidin produced by the pure 

 oil was more firm and coherent than that of 

 the adulterated oil, and was of a lighter col- 

 or, and the nitrous fumes rose more rapidly 

 through the pure oil. The adulteration of 

 the oil was also shown by the fact that it 

 could not be completely saponified with caustic 

 soda, while such saponification is one of the 

 characteristics of pure lard-oil. Pure lard-oil 

 gives with nitric acid a yellow color, approach- 

 ing orange, while the adulterated sample with 

 nitric acid of the same strength gave a distinct 

 brown color on standing. That portion of the 

 oil which resisted saponification with caustic 

 soda gave a much darker, deep coffee-brown 

 color. The determination of the specific gravi- 

 ty is the most important of the physical tests. 



The history of the development of the coal- 

 tar colors has been reviewed, and the colors 

 themselves and the processes for producing 

 them have been carefully described, by Dr. W. 

 H. Perkin in a president's address to the Soci- 

 ety of Chemical Industry, which is published 

 in full in "Nature" of July 30 and August 

 6. At the close of his address, Dr. Perkin 

 invites attention to the fact that the coal-tar 

 industry, to which none other can be com- 

 pared for its rapid progress, is the offspring of 

 chemical research, and that in return it has in 

 many cases given a fresh impulse to research 

 by opening up new subjects of theoretical in- 

 terest for consideration, and from the fruits 

 thus resulting reaping further benefit. This 

 linking together of industrial and theoretical 

 chemistry has undoubtedly been the great cause 

 of its wonderful development. We have now 

 not only all the colors of the rainbow, but 

 we have also the more somber but not less 

 useful colors, and great varieties of products 

 of similar colors possessing different proper- 

 ties which fit them for special uses. This in- 

 dustry is also one of no mean dimensions, and 

 the value of its annual output is estimated by 

 Dr. Perkin to be not less than 3,500,000. 



W. French Smith has made investigations to 



