July 2, 1886.] 



SCIENCE. 



9 



rigid and scientifically controllable conditions can 

 the evidence of such abnormal sensibility be relied 

 upon. Even the precautions against indications 

 as above described would probably have to be 

 added to, if hypnotic subjects were experimented 

 upon. 



In conclusion it is desu'ed to lay stress not only 

 on the negative character of the results, but on 

 the method employed, and especially on the fact, 

 that, as the precautions were rendered more and 

 more effective, the negative character of the con- 

 clusions became more and more evident.^ 



Joseph Jastrow. 



LONDON LETTER. 



No more mteresting and valuable report has 

 been presented to parliament during the recent 

 session than that of the inspectors of explosives 

 for 1885. Colonel Majendie and his colleagues 

 have been engaged for ten years in protecting the 

 public against the most terrible dangers to which 

 modern science has exposed it. A list of twenty- 

 nine men is given who have been caught and 

 punished for complicity in what are usually known 

 as dynamite outrages. In 1885, 133 ordinary ex- 

 plosions due to accident came under the notice of 

 the Home office, and some almost incredible 

 stories are told of carelessness in connection with 

 explosives. The explosion of tablets of chlorate 

 of potash in the pocket of a gentleman in Brook- 

 line, Mass., who dropped his watch upon them 

 quickly, is characterized as the most curious ex- 

 plosion of the year. Among other ' explosive 

 medicines ' is mentioned nitro-glycerine, which is 

 made up with lozenges, etc., for use in cases of 

 angina pectoris and other complaints. In the 

 United Kingdom, 22,268 houses are registered 

 for the keeping of explosives. It is the duty of 

 the local authorities to see that the provisions of 

 the act are complied with. Sometimes, however, 

 they are very remiss, and the inspectors act as 

 a useful check upon them. In 1885, 392 places 

 where explosives were kept for retail sale were 

 Inspected, and in some cases they were found to 

 be 'about as bad as they could be.' London, 

 Liverpool, Bristol, Birmingham, Sheffield, Hud- 

 dersfield, and Bath are selected for special com- 

 mendation in this respect. 



At the last meeting of the London section of 

 the Society of chemical industry, a very valu- 

 able paper was read by Dr. Meymolt Tidy on the 

 chemical treatment of sewage. Premising that 



1 The above is simply a general account of tbe experi- 

 ments. For a detailed account, the reader is referred to 

 the full paper on the subject, to appear in the next number 

 of the Proceedings of the American society for psychical 

 research . 



he had for many years read every thing he could 

 get hold of on the subject, and had also gained 

 practical personal experience therein, he defined 

 sewage as " the refuse of communities, their hab- 

 itations, streets, and factories." Its very com- 

 plex nature was commented upon. Two elements 

 were constant, and ' the rest nowhere : ' viz., 1°, 

 excreta (every thousand people gave, on a very 

 large average, 2,640 pounds of liquid, and 141 

 pounds of dry, sewage daily) ; 2°, roads (if wood- 

 paving be excluded, road-washings contained, on 

 an average, 280 grains of solid matter per gallon, 

 of which 120 were in solution). The extreme 

 difficulty of obtaining fair samples was amusing- 

 ly commented on ; and the salutary effects on 

 sewage, of air and of dilution, as shown by the 

 appearance therein, or otherwise, of compara- 

 tively high forms of microscopic life, such as the 

 Vorticella, Rotifera, etc., was pointed out. An 

 vmfailing characteristic of sewage was the pres- 

 ence of hairs of wheat, and of free spnal cells, 

 their casing having been dissolved in digestive pro- 

 cesses. Authorities were agreed upon two points ; 

 viz., that the valuable matters were in solution, 

 and the offensive in suspension. Irrigation could 

 not be relied on for giving absolutely continuous 

 purity. Of the precipitation processes, those in 

 which lime and alumina were employed succes- 

 sively, gave the best general results ; and the 

 smell still remaining might be entkely got rid of 

 by causing the effluent to flow over a little land. 

 This combination was probably the best method 

 of dealing with liquid sewage ; but, in Dr. Tidy's 

 opinion, the whole system of water-carriage of 

 sewage was a mistake. It was absurd to take 

 expensive and elaborate precautions about purity 

 of water-supply, and then only to use one-nine- 

 tieth of this for drinking, allowing the rest to be 

 polluted. The dry-earth system of dealing with 

 human excreta was the only proper and scientific 

 method. 



The second, and ladies', conversazione of the 

 Royal society was held on the evening of Jtme 

 9. Many of the objects of interest exhibited at 

 the former one were on view again. Among the 

 novelties were the following : some microscopic 

 sections, diagrams, and specimens illustrating the 

 alteration artificially produced m vitreous rocks 

 by the action of heat alone, by Mr. F. Rutley : 

 floral studies in Chili, of orchids, nests, etc., by 

 Miss North ; illustrative diagrams of and speci- 

 mens from Roraima ; some rare eartlis from 

 Samarskite, Gadolinite, etc., with illustrations of 

 then phosphorescent specti-a, by Mr. W. Crookes ; 

 pumice, volcanic ash, drawings, diagrams, etc., 

 illustrative of the great volcanic eruption, by the 

 Krakatoa committee of the Royal society; ap- 



