CHEMICAL SCIENCE. 343 



4th. That the main agent in producing the characteristic reaction was 

 lactic acid. 



Important observations were abo made by Dr. Smith upon the influence 

 of the gastric juice upon the various alimentary principles. These observa- 

 tions, "which do not admit of sufficient abridgment for rcpublication in these 

 pages, may be found in a memoir recently issued by Dr. S. on this subject. 



ON THE USE OF PURE CARBON AS A MEDICINE. 



At the Dublin meeting of the British Association much interest was cx- 

 cixd in a theory brought forward by Mr. Jasper Rogers, in favor of the use, 

 medicinally, cf a pure carbon, which possesses the power of absorbing many 

 volumes of gases which act injuriously upon the human system. Pie exhibited 

 several preparations prepared for this purpose from carbonized peat, and 

 testimonials of their value from eminent medical authorities. 



EXCRETORY PRODUCTS OF LONDON. 



Taking the adult population of London at 2,000,000, and assuming that 

 all the solids secreted by their kidneys are carried into the Thames, the river 

 must hold in solution, or have suspended in its waters, a mean daily supply 

 of one hundred and eighty-one tons of solid urinary products. The quantity, 

 however, varies with the weather ; for, according to the above results, the 

 Thames will contain ten tons more on days when the readings of the barom- 

 eter and thermometer are decreasing than when they arc increasing ; a daily 

 mean of three tons more when the humidity of the air is decreasing than 

 when it is increasing ; seven tons more on ozone days than when there is no 

 ozone ; about ten tons more with south than with north winds, and a daily 

 mean of seventy-five tons more during calm and gentle variable breezes than 

 when there is a current of air. Let agriculturists bear in mind, that from 

 the action of the kidneys alone of a London population, GG,01G tons of British 

 guano are annually swept into the Thames. Dr. Mojfatt, in Medical Times 

 and Gazette. 



AMMONIA IN DEW. 



M. Boussingault has communicated to the Academy of Sciences of Paris, 

 some interesting determinations as to the quantity of ammonia contained in 

 dew. The clew collected on six different nights between the middle of 

 August and the end of September, at Liebfraucnberg, contained on an aver- 

 age 4 - 92 milligrammes per litre (about 0'3 grain per gall.) This shows the 

 nutritive effects of heavy dews. M. B. also showed how this ammonia was 

 absorbed by porous substances. The following substances pulverized and 

 exposed to the air for two or three days, absorbed the amounts of the gas 

 noted. 



Brick 0-0000005. Sand, 0-0000008. 



Phosphate of lime, 0-0000008. Wood, charcoal, 0-0000029. 



Repeating his experiments in Paris, obtaining the dew artificially by con- 

 densing the moisture of the air upon a cold cylinder of metal, he obtained 



