CHEMISTRY. 



107 



the heat given out when the sulphuric acid 

 combines with potash exceeds that given out 

 when the oxalic acid combines with the same 

 base by 0.320, the corresponding differences 

 in the case of soda and ammonia being 0.313 

 and 0.328. If, in like manner, we compare 

 the differences between the heat disengaged 

 by the acetic and tartaric acids, we fall upon 

 the numbers 0.012, 0.122, and 0.116. Even 

 in the case of the oxalic, hydrochloric, and 

 nitric acids, which disengage so nearly the 

 same amount of heat, the same order is ob- 

 served with the three bases. 



Ozone and Hygiene. From January, 1869, 

 to February, 1871, Dr. Cohen, of Quincy, 111., 

 was engaged in taking daily ozonometric ob- 

 servations. In all that time there was not a 

 total absence of ozone from the atmosphere for 

 more than three or four days at a time, and 

 this occurred only in very cold weather. Dur- 

 ing that period Dr. Cohen and his medical 

 brethren of Quincy remarked that less of 

 malarial disease existed then than ever be- 

 fore, and indeed exhibited a marked decrease ; 

 while, on the other hand, catarrhal and bron- 

 chial affections increased in prevalency. In 

 a communication to a Quincy paper, the author 

 says : 



Within the last few weeks there has been a remark- 

 able exemplification of the effects of the sudden ap- 

 pearance of a large amount of ozone in the atmos- 

 phere ; from the latter part of January to February 

 6th, there had been a considerable quantity indi- 

 cated ; and it will be recollected that catarrhal and 

 eruptive fevers were then quite prevalent. On Feb- 

 ruary 6th, the ozonometer recorded " highly intense," 

 and from February 7th to March 10th, inclusive, the 

 record was u none," with the exception of one day, 

 February 26th, on which it was ** moderately in- 

 tense," and five other days, at intervals, on which 

 there was a slight indication. During this period, 

 the complaints I have mentioned disappeared, but, 

 on March llth the record was again " highly intense," 

 and has remained fluctuating with a tendency to a 

 high degree up to this day. Mark the results : in- 

 fluenza, bronchitis, tonsillitis (which some sharp 

 practitioners have dignified with the title of diph- 

 theria, a disease which never appears unless there is 

 a continued excessive amount of ozone present), 

 some cases of pneumonia, and other severe catarrhal 

 affections, have appeared as if by magic, while inter- 

 mittent, remittent, and typhoid fevers often preva- 

 lent at this season, hut never when those affections 

 I have mentioned are rife are scarcely, if at all. 

 heard of. 



He thus recalls his experience in the same 

 line of investigation in New Orleans : 



During the epidemic of yellow fever in New Or- 

 leans, in 1867, not a trace of ozone could be dis- 

 covered ; and, by the observations of Prof. Ford and 

 myself, this condition of the atmosphere continued 

 during the entire winter following, which was marked 

 by the prevalence of an unusual number of cases of 

 malarial fevers, characterized by various types. In 

 the autumn and winter of 1868, however, according 

 to the observations of Prof. Ford, a very large amount 

 of ozone was constantly present, and, while, for the 

 first time in many years, not a single genuine case 

 of yellow fever was reported, and much less than the 

 usual amount of intermittent, remittent, and typhoid 

 fevers prevailed, influenza, diphtheria, and* pneu- 

 monia, became almost epidemic. 



A writer in the American Journal of Science 

 sums up the recent investigations of Engler 

 and Nasse as follows. Following Meissner's 

 method, they used an ozonizing tube 85 centi- 

 metres long, containing 28 wires enclosed in 

 glass, and a coil sufficiently powerful to render 

 the entire bundle of electrodes luminous in 

 the dark : 



If the ozonized oxygen be passed through a U-tube 

 30 centimetres long and one centimetre in diameter, 

 containing zinc-sodium in fragments, the ozone odor 

 disappears completely. If the same tube be placed 

 between the potassium iodide solution and the water 

 over which the cloud appears, the formation of the 

 cloud is not interfered with ; thus showing that it is 

 only the ozone and not the antozone which is de- 

 stroyed by the zinc-sodium. Since Meissner con- 

 cedes that the ozone must be removed to detect the 

 antozone, it follows that, were the antozone formed 

 in the electrizing tube, the gas issuing from it after 

 passing through the zinc-sodium tube, and thus being 

 deprived of ozone, should, on bubbling through 

 water, produce a cloud ; but this the authors find o4 

 to be the case. Moreover, they show that, if the 

 stream of oxygen issuing from the potassium iodide 

 solution be passed through a tube 2.3 metres long, 

 filled with fused calcium chloride, the antozone dis- 

 appears ; while ozone passed through such a tube is 

 unaffected. But, if the gas from the ozonizing tube be 

 passed directly through this calcinm chloride tube, 

 then through potassium iodide solution and then 

 through water, the cloud appears with full strength. 

 Engler and Nasse hence infer that the antozone is 

 formed when the ozone is destroyed in presence of 

 water, and only then. Whence they conclude, with 

 Von Babo and Weltzien, that antozone is only hydro- 

 gen peroxide. In support of this view they give the 

 following experiments : 1. The stream of electrized 

 oxygen, deozonized by a solution of potassium iodide, 

 was passed through a spiral tube 1.5 metres long, 

 and found to give the mist on passing through water. 

 This spiral was then heated in a zinc chloride hath ; 

 as the temperature rose, the mist formed became less 

 and less, disappearing completely at 170, and re- 

 turning again as the tube cooled. 2. The stream of 

 deozomzed oxygen was passed through a short tube 

 containing fragments of potassium hydrate, and then 

 through four narrow tubes 60 centimetres long filled 

 with glass fragments ; but its mist-forming "power 

 was hardly weakened ; when these tubes were cooled 

 to 20, however, no mist appeared on passing it 

 through water ; and, when two narrower and empty 

 tubes were used, and the stream of gas continued 

 for 24 hours, water condensed in them which gave 

 the reactions of hydrogen peroxide. In conclusion, 

 the authors show that the division of oxides by 

 Schonbein into ozonides and antozonides is not well 

 founded. 



Indigotin. Commercial indigo contains 

 from fifty to sixty per cent, of pure indigo-blue, 

 the remainder being gluten and various resin- 

 ous substances formed indirectly from tbo 

 decomposition of the indigo-blue, or directly 

 from the indigo-plant itself. Certain matters 

 are also added occasionally as adulterants. 

 The laboratory mode of purifying commercial 

 indigo is to treat it successively with dilute 

 sulphuric acid, with boiling water, and with 

 alcohol ; but this treatment does not yield a 

 chemically -pure product. The dyers' method 

 of purification gives a better result ; it consists 

 of converting indigo-blue into indigo-white by 

 reducing agents, and, subsequently, reoxidizing 

 it. MM. d'Aguier and Baeyer have recently 



