Chemical Changes in the Fermentation of Duurj. 341 
on the other by 3G4. The history of the missing sulphuric acid 
is intelligibly indicated by the one j)art of sulphuretted hi/drof/en 
found at the montli's end, and I suspect the same indication 
would have been given with regard to much of the missing phos- 
phoric acid if its decomposition did not happen to yield a gas 
comparatively insoluble, and the analyst had been at all sus- 
picious of its existence. Sprengel (Stephens, I. 484) gives both 
sulphuretted and phosphuretfed hydrogen as products of the 
fermentation of the food in the bodies of animals, and what dif- 
ferences can be indicated between this and the fermentation of 
the manure heap, either in the substances fermented or in the 
modes of their fermentation ? A distinct cliemical change takes 
place in the arrangement of the elements of food ivlnch is not required 
to sustain an animaVs vital poivers, and the object of that change is 
the fitting the useless material to become part of other plants ; and 
loliether in tlie body or out of the body the change is the same, and 
once begun it continues its operation till it attains its end. 
The legitimate object of the farmer is the conversion of all his 
waste phosphorus into such a state of combination that it may- 
assist to increase his crops, and that state of combination we at 
present believe to be an equivalent of phosphorus with five 
equlvidents of oxygen. By the common management of his 
manure he not only in a measure misses this, but actually con- 
verts one of its most valuable constituents into a useless and 
volatile substance which may benefit another when it has suffered 
oxidation, but which Is worthless to himself. 
The importance of sulphur in agriculture can hardly be over- 
rated. When we consider that 5 per cent, of all the hair on our 
cattle and wool on our sheep Is sulphur which is all derived 
from their food, and that no albuminous compounds can exist 
without it, we are led to a due estimate of its importance in 
manure. According to received views this body must be com- 
bined with three equivalents of oxygen before it is in a form 
suited for the food of plants, through which it passes before it 
can be of service to animals. 
Sulphur in the state of sulphuric acid has also a high value of 
an indirect kind. It unites with and retains the volatile and 
valuable ;immonia, and yet while fixing It In no dcgi"ee diminishes 
its solubility. It also unites with various other bases and forms 
salts of great agricultural importance. 
The note quoted from Rose, p. 337, states that part of the sul- 
phur in albuminous compounds is unoxidized, and that this is so 
may easily be proved. Dissolve the albumen in potash, add 
acetate of lead as long as the precipitate formed is redlssolved 
and heat the solution to the boiling point. It instantly becomes 
