REPORT OF THE CONSULTING CHEMIST FOR 1918, 125 



The third waste material was a fertilizer made from leather dust, 

 this latter having been treated with sulphuric acid with the object of 

 rendering the nitrogen soluble and available. To a certain, but limited, 

 extent this had been effected, the material showing on analysis : — 



per cent. 



Total nitrogen ...... 6-50 



Readily available nitrogen . . . -32 



About one-third of the nitrogen in organic form was soluble in 

 water, but it remains open to question how far this would be of practical 

 utility. Undoubtedly it would be a great benefit if one could convert 

 old leather scraps &c. into some form in which they might benefit 

 the land, but, so far, leathei has been looked on, and with good reason, 

 simply as a material for adulterating artificial manures and making 

 them show a fictitiously high analysis. Whether the leather, finely 

 ground and treated as above, is of different nature and has any worth, 

 must be left for experimental inquiry. 



5. Lime. — A material sold as a fertilizer under the name " Carbo 

 Limo " was sent me by a Fellow of the Society, who had purchased 

 it at the price of 35s. a ton at the works. It was stated to come 

 from cement works. The analysis was : — 



per cent. 



* Lime ........ 53*62 



Oxide of iron and alumina .... -69 



Carbonic acid &c. ...... 42-33 



Insoluble siliceous matter . . . . 3-36 



ioo-oo 



♦equal to carbonate of lime .... 95*75 



This was practically pure carbonate of lime, and it was, further, in 

 nice, dry, powdery condition. Still, the price, in comparison with 

 that of burnt lime (which has nearly twice as much lime in it) is much 

 too high. 



6. Miscellaneous. — A sample of sand used in potting was sent me, 

 as this was suspected of having done injury to young seedlings, for 

 which it had been used. I thought it possible that the sand con- 

 tained excessive amounts of salt, but analysis of it proved this not 

 to be the case, the sand being perfectly good. 



The remaining sample under this head was one of clay, which it 

 was thought might prove to be " Fullers' Earth." Analysis, it may 

 be pointed out, is, in itself, no clear guide as to whether a clay be 

 Fullers' Earth or not, and the only real guide is the practical applica- 

 tion of tests for its absorptive and decolorizing properties, chiefly 

 as regards its behaviour to oils. So far as indications went in this 

 case, the material answered to the description. 



A few matters of consultation and examination of materials used 

 at the Society's Gardens at Wisley completed the work of my 

 Department. 



