MANURES AND MANURING 



1253 



render it clearly evident that tchernozioni is sufficiently rich in crude ele- 

 ments, both in the form of vegetable and animal residues and in other forms 

 with which, under conditions favourable to the process of disintegration and 

 synthesis brought about by bacteria, a remarkable storage of the fertilis- 

 able substances assimilable b}' plants may be created. 



961 - Study of the Nitrification of Different Leathers available for Agricultural Use, and 



Sulphurated Rape Cakes. — Guillin (Director of the I^aboratory of the Society of 

 Agriculturists of France), in Comptes Rendus de V Acadcmie d' A sericulture de France, Vol. II ^ 

 Year 1916, No. 27, pp. 760-769. Paris, 1916. 



Crude tanned leather has long been regarded as a product which only 

 decomposes slowly in the soil. During the last few j-ears another kind of 

 leather, chrome leather, has appeared on the manure market. This leather, 

 owing to its almost white colour (pale green), is rarely sold under the name 

 of leather, but is marketed in the form of shaviiigs. This chrome leather, 

 of non -putrescent substance, may a p/i. t'i be regarded as not subject to 

 rapid decomposition. Experiments were undertaken with the object of 

 ascertaining whether this view was correct. 



The attempt has been made to render the leathers more easily decom- 

 posable in the soil b}' various processes. The most usual of these processes 

 is roasting ; roasted leathers are in almost all cases rendered slightly acid 

 by the addition of a small quantity of sti'lphuric acid, but this quantity is 

 altogether insufficient to render their decomposition in the soil easier. Be- 

 sides this, some mantif actitrers have sought to transform leather completely 

 by dissoK-ing it in sulphuric acid, afterwards saturating the excess of 

 acid so as to obtain a manure in powder form put on the market under 

 different names : azotine, nitrogene, etc. Two of these dissolved leathers 

 were studied by the writer : for one, sulphuric acid was used in such a 

 qtiantity as to convert the leather waste into a pasty mass. For the other, 

 the quantity of acid used was greater and the mass was liquefied. The study 

 related, in brief, to the comparative nitrification of tanned leather, chrome 

 leather, roasted leather and leather dissolved in sulphuric acid in a paste 

 and in liquid form, as well as the nitrification of sulphurated rape cake. 

 Dried blood was taken as a standard of comparison. 



Composition of the Manures stiidied. — The composition of the manures 

 studied is shown by the following table : 



Dried blood 



Tanned leather 



Chrome leather .... 

 Roasted leather .... 

 Dissolved leather (paste) 

 Dissolved leather (liquid) 

 Sulphurated rape cakt . 



Mode of Procedure. — The nitrification experiments were carried out 

 with clayey-lime soil of the basin of Paris (Gournay, Seine-et-Oise); this 



