1895.] . PUBLIC DOCUMENTING. 33. 287 



factory utilizes all such kinds of waste as have already been 

 referred to. 



lluntje * speaks of rendcrinfii: leather and wool more avail- 

 able by dissolving them in a mixture of GUuil)er's salt and 

 quick-lime. This chemist manufactured a fertilizer upon a 

 larue scale from these materials. 



Keichardt j describes his method of subjecting the leather 

 refuse to steam pressure, and then drying it quickly. After 

 such a treatment he found 15.75 per cent, of the material to 

 be soluble in boiling water, and that, after standing for some 

 time, 20 per cent, could l)e dissolved. By treating the dry 

 leather that had been subjected to steam with 20 to 40 per 

 cent, sulphuric acid, he was enabled to dissolve fi-om 22 to 

 29 per cent, of the leather in water. With a five per cent, 

 solution of crystallized soda, 28.8 per cent, could be brought 

 into solution. He therefore concluded that the best method 

 was to subject the leather to the action of a weak soda 

 solution. 



Coignet's J method was reported in 1874 by H. Mangon. 

 Briefly stated, it is as follows : the refuse material is placed 

 in a room having a cubic area of 20 meters. Directly out- 

 side of the room is a coke oven, connected with a chimney 

 that has an opening into the room containing the material 

 to be treated. Into this chimney are conducted jets of 

 steam, so that the room is heated from 150° to 100° C. 

 for seA^eral hours by this moist chimney air. Under these 

 conditions the leather swells somewhat, and becomes dark, 

 brittle, and can easily be rubbed to a powder. 



Storer § says: "It is evidently with reference to this 

 process that the statement has recently been made that 

 certain manufacturers of fertilizers at Paris devote them- 

 selves particularly to the preparation of torrefied wool, horn, 

 leather and even bone, the leather having first been steamed 

 strongly to remove oil and gelatine." 



L'Hote II describes a method whereby such waste material 



* Jahresbericht Asrric. Chem., 186."). 



t Zeitschrift for deutscbe Laiidwirtschaft, 1865, 136. Jahresbericht Agric. Chem., 

 1865. 



X Organ der Vereinf. Riihenz. Industrie in (Ester-Ungarn, 1874, 32. Jahres- 

 bericht Agric. Chem., 1873-1874, 37. 



§ Agriculture I., 382. 



II Centralblatt far Agric. Cliem., 5. 258. Illustrirte Landw. Zeitung, 1874, No. 2, 18. 



