TRANSACTIONS OF THE SECTIONS. 65 



cient silica to render it very hard and durable. The amount of silica varies in dif- 

 ferent specimens. The following analyses show the composition : — 



Pink. White. 



Calcium carbonate 70-85 50-70 



Calcium sulphate trace 



Magnesium carbonate .... 2-35 37-92 



Peroxide of iron 3-40 



Calcium phosphate 0'80 



Silica 10-18 



Hornblende 23-40 



Water 0-40 



100-00 10000 



The proportion of hornblende in the pink marble is variable. 



On the Retention of Organic Nitrogen by Charcoal. 

 By Edwaed C. C. Stanford, F.CS. 



This paper -was a continuation of one read by the author at the Exeter Meeting 

 last year, entitled " A Chemical Method of treating the Excreta of Towns. " In this 

 paper the value of the dry as opposed to the water-closet system was warmly advo- 

 cated. It was shown that the only two real disadvantages alleged against the appli- 

 cation of the dry system to large towns were : — 



1st. The large quantity of valueless material required to te carted in and out; 

 and 



2nd. The difficulty of obtaining the necessary supply. 



These two difficulties are at once removed by the process proposed by the author. 

 Instead of earth, X-charcoal, or charcoal derived from the carbonized excreta, is 

 used as the deodorizer; of this, in proportion to earth, only one-fourth of the 

 quantity is required, while the substance removed aflbrds by reburning the neces- 

 sary supply. The daily increase of this is available for manure. So far, therefore, 

 from being applicable only to small towns, the system must pay best where the 

 population is the densest. The niti-ogen, phosphoric acid, and potash are all re- 

 tained ; and the expense of removal m proportion to that by water carriage is 

 intinitesmal. 



Houses properly constructed are only visited once a-year, and the removal is less 

 in amount, and even less disagreeable, than that of the house ashes. All the malaria 

 and other evils of connexion with sewers are avoided, and health is ensured. 

 Twelve months' experience on a lai-ge scale are stated to have fully demonstrated 

 all the advantages claimed for this process, and proved it an efficient solution of the 

 sewage difficulty. As, however, some chemists have assumed that the action of 

 charcoal on animal nitrogenotis matter is to oxidize it into nitrates, this was made the 

 subject of a special investigation. The author showed in his former paper that 

 excreta being already an oxidized product, there was little foundation for this as- 

 sumption as far as regards this animal matter. Now he also shows that even meat 

 when dry is unaffected by either X-charcoal or seaweed charcoal. Mixtures of these 

 charcoals with meat and with solid and fluid excreta were allowed to become dry, 

 and then tested monthly for nitrogen for six months. It was found that there was 

 no loss of nitrogen, no oxidation, and no formation of nitrates. As this result is 

 contrary to the usual view, further experiments with other charcoals are promised. 



Dtist as a Ferment. By Chakles E. C. Tichborne, F. O.S., M.R.I.A. 



The author's paper was an attempt to deal with the chemical activity of dusts as 

 actual ferments. He referred to his researches in 1866 (the cholera year), in which 

 he demonstrated that the organic portion of street dusts in large towns consisted of 

 stable manure finely ground. Such dust generally gives an acid reaction, but there 

 were some cases taken from the locality of cab-stands which presented traces of 

 ammonia. The following is one of the specimens given : — 



1870. 5 



