114 



CHEMISTRY. 



water, with a solubility rapidly decreasing with 

 increase of carbon atoms. Acids decompose 

 them in the cold, with assimilation of water, 

 into their constituents, but they are compara- 

 tively stable toward alkalies. Light exerts a 

 decomposing action upon them ; specimens 

 placed in bright sunshine rapidly become yel- 

 low. Reducing agents are without action upon 

 them, and they appear further to be incapable 

 . of reducing either Fehling's solution or (except 

 after long boiling) ammoniacal solutions of sil- 

 ver salts. 



New Processes. India-rubber is usually vul- 

 canized by heating it with sulphur until chemical 

 combination takes place. A different method is 

 pursued in making cloth for waterproof garments. 

 The cloth is washed with a solution of chloride 

 of sulphur in bisulphide of carbon, when the fa- 

 bric is heated to evaporate away the excess of those 

 substances. The chemical action in the process 

 is supposed to be represented by a combination 

 of the sulphur with the India-rubber, producing 

 vulcanization, and of the chlorine with the hy- 

 drogen to produce hydrochloric acid. This re- 

 action, Mr. William Thomson believes, is not 

 the correct one, while the reverse is probably 

 more in accordance with the facts, viz., that the 

 chlorine of the sulphur chloride combines with 

 the India-rubber to produce vulcanization, while 

 the sulphur is left free or only partially in com- 

 bination with the rubber. Mr. Thomson sup- 

 ports this view by citing certain results of his 

 own experiments. A substitute for India-rub- 

 ber which is much used is produced by acting 

 on vegetable, oils with the solution of chloride of 

 sulphur in bisulphide of carbon. The oil be- 

 comes converted into a solid substance some- 

 what resembling India-rubber, but more brittle. 

 Mr. Thomson's analyses of this substance have 

 invariably shown it to contain a much greater 

 proportion of chlorine than of sulphur. The 

 process is therefore probably a vulcanization by 

 chlorine rather than by sulphur. The substi- 

 tutes contain considerable quantities of oily mat- 

 ters soluble in water, which have also been found 

 to be chlorine and sulphur compounds of the 

 oils. These oily matters are supposed by some- 

 manufacturers to be injurious to the rubber, but 

 the author has found that it rather acts as a 

 preservative of it. Copper salts exert an injuri- 

 ous effect on India-rubber, and cloth that has 

 been dyed with them is destructive to a coating 

 which may be placed upon it. 



The authors William Thomson and Frederick 

 Lewis continued their experiments on the action 

 of copper and other metals and their salts on 

 India-rubber. A sheet of India-rubber was 

 spread on paper and vulcanized. The sub- 

 stances filings of metals or solutions of salts 

 were placed upon small squares of the rubber 

 and exposed to a heat of 140 F. for ten days, 

 when the rubber on each square was tested. 

 Copper was found to have a destructive effect 

 far beyond that of the other metals. The fol- 

 lowing metals were destructive in the order in 

 which they are mentioned : Platinum, palladi- 

 um, aluminum, and lead. Magnesium, zinc, cad- 

 mium, cobalt, nickel, iron, Chromium, tin, ar- 

 senic, antimony, bismuth, silver, and gold had 

 1*0 effect upon the rubber. Of salts, besides 

 those of copper, arsenic iodide, silver nitrate, 



strontium, chlorate, vanadium chloride, red and 

 black oxides of manganese, and bismuth chlo- 

 ride destroyed the rubber ; ferrous nitrate, sodi- 

 um nitrite', uranium nitrate, and ammonium 

 vanadate considerably damaged its elasticity; 

 lead chromate, ferrous sulphate, zinc acetate and 

 chloride, tin peroxides and perchloride, chromic 

 acid, and lead borate only slightly damaged it. 

 Copper salts were found to damage it even in 

 minute quantities and in proportion to the quan- 

 tity of copper present. Experiments on the 

 action of different cloths and cloths of different 

 colors likewise demonstrated the injurious effect 

 of copper. Of acids of a strength to neutralize 

 equal parts of a 10-per-cent. solution of anhy- 

 drous sodium carbonate, nitric acid was de- 

 structive, while hydrochloric, sulphuric, chromic, 

 citric, and tartaric acids were not ; but rubber 

 soaked in the strongest sulphuric-acid solution 

 containing 10 per cent, of acid was destroyed on 

 being heated to 212 F. Peroxide of hydrogen 

 appeared to be neutral in effect, while ozone 

 had been previously found to be destructive. 

 The opinion of manufacturers that over-masti- 

 cation of India-rubber is injurious was not borne 

 out by the experiments. 



Having found that gold can be completely 

 precipitated by the electric current from its 

 double cyanides, Edgar F. Smith and F. Muir 

 attempted to decide what metals can be sepa- 

 rated from gold in this manner. Their experi- 

 ments were satisfactorily successful in the sepa- 

 ration of gold from copper, from cobalt, from 

 nickel, from zinc, and from platinum, and of 

 silver and mercury from platinum. With cad- 

 mium the precipitate was never free from plat- 

 inum. The electrolytic separation of zinc from 

 mercury, cadmium, and silver in a solution of 

 potassium cyanide was effected without diffi- 

 culty. 



To detect contamination of water with sew- 

 age, Peter Griess dilutes- paradia- benzol sul- 

 phuric acid with 100 parts of water and adds a 

 little soda lye in excess. The solution must be 

 used when fresh, as it soon becomes colored 

 spontaneously. If when it is introduced into 

 the water no change of color takes place within 

 five minutes, the total absence of organic secre- 

 tions or products of decomposition may be in- 

 ferred. A yellow color shows the presence of 

 such matter in proportions corresponding with 

 its tone. With this test the author has made 

 very delicate determinations. 



A method of making phosphorous oxide by 

 burning phosphorus in the air is described by Prof. 

 T. E. Thorpe and A. E. Tutton. Pure phosphor- 

 us oxide crystallizes in thin monoclinic prisms, 

 melts at 22'5, solidifies at 21 , and boils unchanged 

 in an atmosphere of nitrogen or carbon dioxide 

 at 173. When heated at 300 it decomposes, and 

 is converted into phosphorus and phosphorous 

 tetroxide. It is readily acted on by light and in 

 bright sunshine turns yellow and eventually dark 

 red. Cold water, contrary to the usual statement 

 of the text-books, has very little action upon it. 

 Hot water acts on it with explosive violence, 

 and the red sub-oxide, phosphoric acid, and 

 phosphoretted hydrogen result. On exposure to 

 the air or oxygen it spontaneously oxidizes to 

 phosphorous pentoxide, with a faint luminous 

 glow if the pressure is diminished. It has well- 



