

CHEMISTRY. (MISCELLANEOUS.) 



CHILI. 



87 



van Kettel in 1897, is based on the presence in a 

 number of fatty oils of minimal quantities of pen- 

 tosanes which are not contained in fats of animal 

 origin. These pentosanes may easily be detected 

 by means of a hydrochloric solution of phloroglu- 

 cine. Shortly after this the author's attention was 

 directed to a reaction discovered by Halphen, in 

 which equal volumes of the oil under examination, 

 amylic alcohol, and sulphide of carbon containing 

 1 per cent, of sulphur in solution, are heated in 

 u boiling salt-water bath for ten minutes or a 

 quarter of an hour, when, if a red or orange color 

 is produced, the presence of cotton-seed oil is in- 

 dicated. For detecting cotton-seed oil in butter, 

 the author dissolved a quantity of butter in ben- 

 zene, and after having filtered the liquid obtained 

 and driven off the benzene by evaporation, added 

 Halphen's reagent to the melted fat and heated 

 half an hour in a boiling-water bath. In 20 ex- 

 periments made he discovered cotton-seed oil in 

 only one sample. The commercial oils are sub- 

 mitted to a series of manipulations for the purpose 

 of improving the smell, taste, and color, and oils 

 thus treated give negative results with colored re- 

 actions. 



Miscellaneous. Attention has been called by 

 Thomas B. Stillman to important variations in the 

 composition of Paris green under the increasing 

 consumption which has been stimulated by its ex- 

 tensive use in horticulture as an insecticide. The 

 article as formerly prepared for pigment purposes 

 was of uniform composition, or nearly so; but of 

 late years, since it has been hurriedly manufactured 

 in enormous quantities, variation in composition 

 has become very marked. The commercial product 

 now fails in many instances as an insecticide; for, 

 when arsenious oxide is present in it combined as 

 arsenite, in certain percentages, its action is nulli- 

 fied. When pure, the composition of Paris green 

 may be stated as an aceto-arsenite of copper a 

 combination of arsenious acid 58.65 per cent., oxide 

 of copper 31.29 per cent., and acetic acid 10.06 per 

 cent. A part of the arsenic may exist as arsenic 

 acid as well as arsenious acid, and copper suboxide 

 may be present in small amounts. Adulteration, 

 in the sense of foreign material added, is rare with 

 manufacturers of Paris green in the United States. 

 The cost of production is lessened by increasing 

 the percentage of arsenic, while the effectiveness 

 of the product as an insecticide may be diminished. 

 Paris green manufactured in Germany is often 

 adulterated with barium sulphate. The chemical 

 examination of Paris green is comparatively sim- 

 ple, since it is soluble in slight excess of ammonia, 

 forming a dark-blue solution; the chemical exam- 

 ination of a sample containing other pigments may 

 or may not be a complex undertaking according 

 to the number of materials that are added. When 

 Paris green is intended for a pigment, foreign sub- 

 stances may be introduced to modify the color, as 

 when chromate of lead is added to lighten it. 



An instance is given by E. T, Allen in which 

 a number of analytical weights of gold-plated 

 brass, put away for the summer in an iron safe, 

 were found, at the end of three months, to have 

 been attacked with moisture. The tops of all the 

 weights were covered with a white substance 

 which could not be removed by brushing or rub- 

 bing, and which, when scraped off, proved insolu- 

 ble in water, but soluble in hydrochloric and nitric 

 acids. The weights were, moreover, abnormally 

 heavy. The presence of organic matter was re- 

 vealed on heating upon platinum foil. Other tests 

 showed that the substance was some compound of 

 zinc probably, it was thought, the hydroxide 

 mixed with mold, or a zinc salt of some organic 

 acid. The action was evidently due to water and 



mold, which were certainly present. It is well 

 known that plated metals at exposed points are 

 more liable to corrosion than either metal alone, 

 owing to electrolytic action. In such cases it is of 

 course the more positive metal which is attacked. 

 This was true in the case under consideration; 

 the zinc was attacked, while the copper and the 

 gold were unaffected. A microscopic examination 

 showed that wherever corrosion had touched the 

 weights the gold had become granulated or blis- 

 tered. The author refers to a case somewhat similar 

 to this, described by Witter, in which the amal- 

 gamated plates of a stamp mill in Smaland, Swe- 

 den, were attacked by the water used, which had 

 its source in a peat bog. 



A paper on The Driving Energy of Physico-chem- 

 ical Reaction and its Temperature Coefficient is 

 contributed to the Proceedings of the American 

 Academy of Arts and Sciences by Prof. Theodore 

 William Richards. In it the author, starting with 

 the close similarity between the equations of Clau- 

 sius and Van t' Hoff, points out the advantages, 

 previously recognized by Arrhenius, of considering 

 pressure to be the fundamental quantity which 

 determines the progress of chemical reactions; and 

 this aspect is believed to afford a more direct 

 method of analysis than the study of volume, con- 

 centration, or energy. An expression called the 

 " reaction metatherm " is evolved, which repre- 

 sents in terms of pressure the temperature coeffi- 

 cient of the equilibrium ratio of ideal physico- 

 chemical reaction. The equation obtained is the 

 mathematical expression of the theorem of Mau- 

 pertuis or Le Chatelier, and when analyzed it 

 shows that the part played by each substance in 

 a reaction may be considered as the logarithm of 

 the product of its " physico-chemical potential," 

 and is actually present pressure. The reaction 

 metatherm may be simplified into a reaction iso- 

 bar, according as the pressure or volume is kept 

 constant during the reaction. While, however, the 

 reaction isobar offers the most convenient basis for 

 calculations to which it is applicable, results under 

 constant volume are more conveniently calculated 

 if the reacting substances are expressed in terms of 

 concentration according to the equation of Van 

 t' Hoff. 



In the course of the president's address before 

 the Society of Chemical Industry, Prof. Chandler, 

 speaking of the work of American chemists, said 

 that many important investigations in agricultural 

 chemistry had been conducted by the chemical 

 division of the United States Department of Agri- 

 culture. Among them were the practical deter- 

 mination of the number and activity of the nitrify- 

 ing organisms in the soil, the influence of a soil 

 rich in nitrogen on the nitrogen contents of a crop, 

 the manufacture of sugar from the sorghum plant, 

 and the comparative study of the typical soils of 

 the United States. Chemists connected with agri- 

 cultural experiment stations had done a large 

 amount of original investigation on subjects more 

 or less closely allied to agricultural and physi- 

 ological chemistry. The author referred to the 

 progress that had been made here in electro-chem- 

 istry, to the method of reducing aluminum prac- 

 ticed at Niagara, to the manufacture of corundum 

 and artificial graphite, and to the expansion in the 

 manufacture of water gas, which is used in whole 

 or in part by 500 gas companies. 



CHILI, a republic in South America. The 

 Congress consists of a Senate of 32 members and 

 a House of Representatives containing 94 mem- 

 bers, the Senators elected for six years in the 

 provinces and the Representatives for three years 

 in the departments by the direct vote of the adult 

 male population. The President is elected for five 



