312 PEAT ASHES. 



»nd sof/ o' h^fba^eois peat. Some of it is cxtremrly compact, 

 Mack, and like veo^etfjble mould in appeanuice ; generally speaking 

 it is light, sponger, ind of a lighter or deeper shade of browa. 

 When quite dry, it is often extremely light ; a *^ub c metre, which 

 is about one-eleventh more ihan ac^ibif. yard, wil weigh from 5 to 6 

 cwt. 



The circumstances in which turf has been found lead us to infer 

 that it must contain the elementary insoluble elements of the plants 

 that produced it. It appears, however, to contain a somewhat lar- 

 ger proportion of azote than the average quantity met with in her- 

 baceous vegetables, supposed dry ; but we have seen that in the 

 slow alteration of lignine, azote becomes concentrated, as it were, 

 in the residue ; and that, in fine, mould contains a larger quantity of 

 azote than the wood from which it proceeds. It appears further 

 from some experiments very lately performed by Mr. Hermann, that 

 during the putrefaction of the woody prmciple, azote is actually ta- 

 ken from the air to concur in the formation of certain products that 

 are perfectly definite. Mr. Hermann quotes the following experi- 

 ment : 



Twenty-eight parts of wood taken from a log already attacked 

 with rot, and in which, indeed, there were several points already 

 decayed, were moistened and enclosed in a jar containing atmo- 

 spherical air over mercury. The bulk of the atmosphere contained 

 in the bell-glass was 262 volumes. The wood was kept there for 

 ten days at a temperature of 75.2° Fahr. The apparent volume of 

 the air continued unaltered to the end of the experiment ; but a 

 large quantity of carbonic acid had been formed : 



RESULTS ON THE I.NCLUDED AIR. 



Before. After. 



The air contained : Azote 207 vols. 194 vols. 



Carbonic acid 40 " 



Oxygen • ••• 5.5 28 " 



ai2 282 



The moist wood in its decomposition during ten days had conse- 

 quently caused thirteen volumes of azote and twenty-seven volumes 

 of oxygen to disappear. And Mr. Hermann found that it now con- 

 tained principles analogous to those of humus, one of which, nitro- 

 lin, is highly azotized, and by the ulterior action of air and moisture, 

 gives rise to ulmate of ammonia. These experiments of Mr. Her- 

 mann are new, and the conclusions to which they lead are both inter- 

 esting and important * 



Turf or peat is virtually the woody principle in the last stage of 

 modification by atmospherical influences ; but it appears still to con- 

 tain, although modified, the usual principles which enter into the 

 constitution of herbaceous vegetables also. M. Payen detected a 

 quantity of fatty matter in it, analogous to that which exists in 

 leaves, and M. Reinsch found it to contain tannin. One sample o( 



* Vide his \M]M'T in Journ. fur prakt. Chernie, b. xxiii. %. 379. 



