58 BULLETIN OF THE BUSSEY INSTITUTION. 
No. 5. — On the Fertilizing Power of Roasted Leather. By 
F. H. Srorer, Professor of Agricultural Chemistry. 
Ir is a familiar fact of agricultural experience that ordinary leather 
is of no use as a fertilizer, excepting in so far as it may sometimes be 
employed for mulching. The fact is one that has specially attracted 
the attention of chemists, since it goes to show not only that the five 
or six per cent of nitrogen contained in leather is useless for feeding 
plants, but that plants need to have their nitrogenous food presented 
to them in fit forms, and that, furthermore, the nitrogen in leather must 
be held in some very peculiar state of chemical combination. 
As is well known, a good part of this inert nitrogen can be recovered 
for use as a fertilizer, by subjecting leather to destructive distillation, 
and collecting the ammoniacal distillate, either in an acid, or in mere 
earth, in case the product is to be used in the immediate vicinity of the 
place where it is prepared. The process recently devised by L’Héte* 
for distilling leather scrap and the like with soda lime, as an economi- 
cal method for the manufacture of ammonium salts, may perhaps turn 
out to be of considerable importance from the agricultural point of 
view. But, aside from actual distillation, it has been suggested at one 
time and another that the inert nitrogen compound in leather could be 
broken up and the nitrogen in it made available for plants, by merely 
heating or “roasting” the leather, at temperatures considerably lower 
than that at which destructive distillation occurs. 
In order to determine whether roasted leather has any fertilizing 
value, I have subjected some of it to the test of practical trial, by 
growing a number of buckwheat plants in jars of earth and of sand, 
each of which contained a definite quantity of the leather, and which 
were moreover supplied, in addition to the leather, with one or more 
of the several kinds of food that are known: to be necessary for the 
growth of plants. ‘The intention was so to arrange the experiments 
that the fertilizing power of the leather, if any there were, should 
have an opportunity to exhibit itself in some one\or more of the jars ; 
that is to say, in those jars whose soils had been purposely deprived 
of that special kind of plant-food which the roasted leather might be 
competent to supply. For purposes of comparison, experiments upon 
* “Chemical News,” 1873, 27. 242. 
