Dec. ii, 1879] 



NATURE 



133 



born at Langues, in Lorraine, July 19, 1793. After 

 completing a course of scientific study, he opened a 

 pharmacy in Paris, where he soon attracted attention by 

 his talent for investigation, as well as by his ability in 

 scientific literary work. In 1S25 he assumed the editor- 

 ship of the Journal de Chimic medicale, and continued 

 this labour until some years prior to his death, having as 

 associates Payen, Pelouze, Robinet, Orfila, Pdligot, 

 Dumas, and other leading chemists of the day. Soon after 

 entering upon his career as investigator, his merits were 

 recognised by the government, and he gave up his business 

 connections to accept the Chair of Chemistry at the 

 Ecole suptirieure de Pharmacie, a position which he 

 occupied up to the time of his death. 



Among Chevallier's earlier researches should be men- 

 tioned his investigations on the absorptive capacities of 

 living plants for various inorganic solutions, and espe- 

 cially his exhaustive studies in connection with Payne, on 

 the hop and the potato, which attracted general attraction. 

 In physiological chemistry notice should be ta'-;en of his 

 detection of various poisonous metals, such as lead and 

 copper, in normal organisms. The knowledge of French 

 mineral waters is also greatly indebted to his numerous 

 and exhaustive analyses, and the presence of arsenic in 

 many springs was first signalled by him. The greater 

 portion of Chevallier's life was devoted to the chemical 

 phases of public hygiene, and in this connection he pub- 

 lished a number of valuable papers on the detection and 

 prevention of adulteration in a large variety of articles of 

 food, methods of preserving food, disinfectants, &c. Of 

 his devotion to the cause of scientific inquiry an interesting 

 anecdote is related from the earlier part of his career. A 

 case of poisoning was to be tried at Paris in which 

 acetate of morphine had been used, and Chevallier, who 

 had sold the salt to the murderer, was summoned as a 

 witness. Anxious to have the full nature of this hitherto 

 untried poison well established, and being limited as to 

 time, he immediately undertook a thorough investigation 

 of its toxic effects on his own system, and succeeded so 

 well that at the trial he was able to give a detailed 

 description of the symptoms attending the use of the drug 

 in question. 



As a scientific writer Chevallier was widely and 

 deservedly known. His first work in 1824, in connection 

 Willi Payen, " Traite des reactifs chimiques," reached a 

 third edition in five years. In 1826-29 nc published, with 

 Richard and Guillemain, an extensive " Dictionnaire des 

 Drogues simples et composees," in five volumes. In 1850 

 appeared his admirable " Dictionnaire des Alterations et 

 Falsifications des Substances alimentaires, mddicamen- 

 teuses, et commerciales," which reached a third edition 

 in 1858, and was translated into other languages. Other 

 important works were " Recherches sur fes Moyens 

 appliquees a la Conservation des Substances alimentaires " 

 (1858), "Du Cafe, son Histoire, son Usage, etc." (1S62); 

 "Traite des Disinfectants sous le Rapport de l'Hveiene 

 publique" (1862). ' 6 



T. H. N. 



THE SEWAGE OF LONDON 



GENERAL SCOTT, in his recent paper at the Society 

 of Arts, entitled " Suggestions for Dealing with the 

 Sewage of London," deserves credit for having drawn 

 attention to a subject which in itself must have especial 

 interest for all residents in the metropolis, but which, 

 from the manner in which he has dealt with it, possesses 

 further attractions for those who have made the scientific 

 aspects of the sewage question their study, in that he has 

 really attacked this much-debated problem in an entirely 

 new direction, and has in so far entered upon fresh 

 ground. We do not remember that any previous investi- 

 gator has set himself the task of examining into the com- 



position and character of the suspended matters of water 

 carried sewage coupled with the possibility of the mecha- 

 nical separation by simple subsidence (1) of the heavier 

 mineral particles or the detritus, and (2) of the lighter 

 flocculent particles, which latter, consisting as they do 

 mainly of the fecal matters, possess a far higher manurial 

 value than the heavier substances washed from the roads 

 and pavements. 



The sludge deposited from sewage by one or the other 

 systems of precipitation has received hitherto the chief 

 share of attention from scientific men, and even when the 

 possibility of recoveringthe solid matters in sewage by some 

 system of straining or rude filtration, or the retention of 

 such solids in tanks, in which the sewage is brought to 

 temporary quiescence, has been considered, it seems on 

 all occasions to have been the practice to regard the entire 

 bulk of such deposits as an inseparable compound of 

 very low value from the manure point of view. It is of 

 course the manurial value of the ingredients contained in 

 suspension and in solution in sewage which has been so 

 frequently inquired into by chemists ; and, beginning 

 with the report of Dr. Hoffman and Mr. Witt in 1857, 

 down to that of Messrs. Rawlinson and Read in 1876, a 

 vast mass of valuable information concerning the nature 

 composition, and value of the manurial elements of town 

 sewage has been accumulated. It has remained for 

 General Scott to point out that — 



1. A very large proportion of the solid suspended 

 matters may be removed from sewage by simple sub- 

 sidence. 



2. That such matters may roughly be separated, the 

 more valuable from the valueless, by the method in which 

 such subsidence is accomplished. 



3. That after such preliminary treatment, any chemical 

 process for the clarification and partial precipitation of 

 the dissolved impurities of sewage may be carried out far 

 more readily, and under conditions rendering their success 

 in an economical point of view one of greatly increased 

 probability. 



4. General Scott has indicated various simple methods 

 for dealing with the silt and detritus removed from the 

 sewage at a relatively small expense ; of deodorising and 

 fitting the sludge obtained by subsidence for the manufac- 

 ture of a manure ; and lastly, a mode of further purifying 

 the London sewage by a system of chemical treatment 

 whereby it may be rendered suitable for discharge into a 

 river of large volume. 



Assuming the dissolved impurities to be incapable of 

 recovery unless the sewage water can be utilised for irri- 

 gation, the first object of General Scott's paper was to 

 show how large an amount of harm was done to rivers 

 and the dwellers on their banks solely by the solid matters 

 contained in sewage. By means of extracts from the 

 reports of the various Royal Commissions who have 

 examined into this question, and the information furnished 

 to the Metropolitan Board of Works by their own advisers, 

 Messrs. Bidder, Hawksley, and Bazalgette, he proved 

 that the deposits in the river, the mud banks, the foul 

 emanations from which were most unhealthy, and the 

 dangers to navigation were all due to the discharge of 

 the solid ingredients of raw sewage into rivers and into 

 the Thames. 



General Scott next entered very minutely into the com- 

 position of the suspended matters of sewage. An estimate 

 of the total weight of solid mattersdue to a mixed population 

 of 3,500,000 persons, with a proportionate allowance for the 

 fertilisers existing in the excreta of animals, together with 

 the dibris of the animal and vegetable substances which 

 might rind their way into the sewers, would manifestly 

 represent the sum total of the organic matters in London 

 sewage. 



Concerning the gross annual amount of organic matters 

 different estimates appear to vary very slightly, and in 

 assuming them in the case of London at 50,000 tons per 



