CHEMISTRY. 



185 



of which he describes in the "American 

 Chemical Journal." The process of separation 

 was as follows : A quantity of the compound 

 CiiClsa, finely divided, was heated in a sealed 

 tube with an excess of aniline for six or eight 

 hours, the temperature during the time not 

 exceeding 180 C. On examination after cool- 

 ing, a deep-rod viscid product was found, 

 which was transferred to a shallow dish, water 

 added, and the whole then heated on a water- 

 batli. Much of the adherent aniline was got 

 rid of in this way, and by repeatedly distilling 

 the residue left after evaporation it was finally 

 obtained in a pure form. The new base thus 

 produced contains chlorine and nitrogen. It 

 forms salts with acids, is easily soluble in 

 water and other solvents, and from concen- 

 trated aqueous solutions after long standing it 

 separates in thin, broad scales, that are near- 

 ly colorless, refract light strongly, carbonize 

 slightly at 225 0., and fuse at 230 0. It 

 forms a salt with hydrochloric acid, charac- 

 terized by very long, broad, colorless crystals, 

 that are readily soluble in water and alcohol. 



Nitric Add from the Electric Light. It is 

 known that when combustion takes place at 

 high temperatures, small quantities of the ni- 

 trogen and oxygen of atmospheric air combine, 

 forming several oxides of nitrogen, many of 

 which are strong corrosive acids. This is the 

 case when electric sparks are passed through 

 air, also during combustion in air of hydrogen. 

 It therefore appears probable that, as the tem- 

 perature of the electric arc is undoubtedly very 

 high, nitric acid or some other oxide of nitro- 

 gen might be produced by the electric light. 

 This subject has been investigated experimen- 

 tally by Mr. T. Wills, with results strongly con- 

 firmatory of this theoretical inference. The 

 first experiment was rather surprising. A 

 glass cylinder placed over an electric lamp 

 (Foucault's regulator) for two minutes, and 

 afterward examined, was seen to contain a 

 perceptible amount of red fumes due to perox- 

 ide of nitrogen (Na0 4 ). The air surrounding 

 the lamp was next drawn through a solution 

 of potash, and the amount of nitric acia esti- 

 mated ; this gave ten to twelve grains of nitric 

 acid produced per hour (it may eventually 

 prove to be more, the difficulty being to col- 

 lect the whole of it). The next step in the re- 

 search will be to examine the various forms of 

 electric light, with a view to determine the 

 amount of nitric acid produced by each. 



Water Examination as related to Health. 

 Dr. F. Holdefleiss, in a recent paper on the 

 examination of water in its relation to the 

 health of men and animals, claims that chemi- 

 cal analysis alone is insufficient to determine 

 the character of water. Microscopic exami- 

 nation promises more satisfactory results, in as 

 far as the organisms observed have been found 

 to bear certain relations to the sanitary value 

 of the water. For purposes of examination, 

 only natural, freshly drawn water should be 

 taken, and that from the bottom or sides of 



the well or tank. Not the number of organ- 

 isms present, but their nature, imi.-t be regard- 

 ed as indicating the condition of the liquid. 

 In their connection with this snbject he classi- 

 fies organisms as follows : 1. Such as can live 

 only in good, sound water ; 2. Organisms free 

 from chlorophyl, nourished solely from putres- 

 cent organic matter, and directly promoting 

 the decomposition of organic matter, nitro- 

 genous or non-nitrogenous organisms which 

 can live only in waters that evince putrefac- 

 tive processes ; 8. An intermediate group, or 

 organisms which can live either in good or 

 bad waters. 



Well-water is to be regarded as pool when free from 

 all organisms, from ammonia, nitrous acid, and hy- 

 drogen sulphide. 



Open waters, flowing or standing, arc good when 

 they contain living green algae and diatoms with the 

 contents of the shells normally colored, but no color- 

 less algae (Beggiatoa, Leptormtvs, etc.), and none, or 

 but few, JSchizomyceteg. 



Drinking-water for human use, in addition to free- 

 dom from all organisms, from ammonia, nitrous acid, 

 and sulphuretted hydrogen, should not exceed 18 20 

 of hardness. If river-water is so purified by filtration 

 that it possesses these properties, and that suspicious 

 organisms do not reappear on standing, it may be used 

 without scruple. 



Open waters containing preen algae and living dia- 

 toms, and free from ammonia and nitrous acid, may 

 be consumed with safety. 



For cattle traces of ammonia and nitrous acid in 

 pond- and river- water may be tolerated if green algro 

 and living diatoms are present. 



Water for fish-ponds should be free from sulphu- 

 retted hydrogen, and should be rejected if Beggiatoa 

 alba is present in a state of normal vitality. Leptomi- 

 tus lacteus is probably dangerous. 



The mere vicinity* of waters containing Beggiatoa 

 and the Schizomycetes is dangerous, as they may in- 

 fect the atmosphere and communicate germs of a dan- 

 gerous nature to the ground- water ana the wells. 



Derivation of Indigo-Blue. Mr. Edward 

 Schunck has recently published the results of 

 an interesting series of experiments on the 

 leaves of the common woad (hatis tinctoria\ 

 undertaken for the purpose of determining 

 whether, as has heretofore been supposed, the 

 indigo-blue obtained from them exists as such 

 in the plant, or is the product of some chemi- 

 cal change occurring to one or more of its 

 constituents during the process of extraction. 

 He finds that the leaves of the plant do not 

 contain either indigo-blue or its hydride ready 

 formed ; but that they yield by careful treat- 

 ment indican, a peculiar glucoside, which, when 

 subsequently treated by acids and other re- 

 agents, breaks up into indigo-blue and indigo- 

 glucine, the latter resembling glucose. He 

 further ascertained that indican is a highly 

 unstable substance, undergoing when its watery 

 solution is heated for some time, or more rap- 

 idly when acted upon by caustic alkalies, an 

 entire change, on the completion of which it 

 no longer yields indigo-blue by decomposition 

 with acids, but in place of the latter gives in- 

 digo-red, indifulvine, leucine, and other prod- 

 ucts. The investigation was afterward ex- 

 tended so as to include Polygonum tinctorium, 



