NITEOGEN FEOM SPENT WASH. 269 



matters, generally lime, in somewhat larger quantity up to 40 per 

 cent. But the fertilizing elements in the products so obtained are 

 present in proportions but little acceptable to farmers, and the pre- 

 sence of inert matters rendered their transport charges heavy. 



Winck has tried to utilize the nitrogen of spent wash as 

 manure. His process consists in concentrating the spent wash to 

 40 to 42° B., then to add massive quantities of sulphuric acid. 

 This acid mixture is afterwards neutralized with carbonate of lime, 

 and dried in stoves. The addition of acid and of carbonate favours 

 the drying, the jpresence of sulphate of lime renders the mass 

 more porous, more easy to treat. The product obtained contains 

 3 to 5 per cent nitrogen and 12 to 14 per cent of potash. Eiviere 

 proposes to separate potash from concentrated spent wash by 

 hydrofluosilicic acid. The organic matter separated from these 

 salts can be evaporated in the same way as in the Vasseux process 

 described below. Effront has likewise introduced a process for 

 separating the organic nitrogen from the mineral substance. This 

 process is based on the observation that the nitrogenous matter of 

 spent w^ash becomes insoluble when it is treated with acid at a 

 temperature of about 200' C. To the concentrated spent wash acid 

 is added to decompose the organate ; the mixture is maintained for 

 some hours in stoves at 190 C. A portion of the nitrogen is dis- 

 engaged and is collected by a fan in the acid. The mass issuing 

 from the stove is crushed, 'then lixiviated with boiling water. The 

 cooled liquid deposits sulphate of potash. The insoluble residue is 

 dried at 100° C. By this method 8 to 9 per cent nitrogen free 

 from potash is obtained. 



Becovery of Nitrogen hy Vasseux s Process.— Bj this method 

 all the nitrogen freed from the greater part of the potash is easily 

 recovered, no noxious principle being generated in the process, 

 which is as follows : The spent wash, previously concentrated to- 

 32° to 35° B., is treated by sufficient sulphuric acid to convert the 

 organates of potash into sulphates. The sulphate of potash formed 

 crvstallizes in the midst of the mass ; it is separated by decantation, 

 filtration, and centrifuging. This sulphate of potash is afterwards 

 washed and again centrifuged. It is then sufficiently pure and is 

 sold as 75 to 80 per cent sulphate. The organic matters which 

 form the drainage^ are ^ then dried in special vacuum machines; 

 decomposition is avoided and the distillate glycerine, tar, etc., may 



be collected. 



^Yhen drying is complete the mass is run into trucks. It is 

 fluid when hot but soon cools into a mass which is broken up^in a 

 crusher. An organic manure is thus obtained containing 6 to 7 per- 

 cent of nitrogen and 6 to 7 per cent of potash. This product, almost 

 entirely soluble in water, nitrifies very rapidly in the soil and suits all 

 crops. For every 1000 kg. (metric ton) of molasses treated 150 kg. 



