THOAIAS-,SLA(i oil BASIC CINDER. -I'M) 



It is unt'ortimate that the samples of slag used in mauy of 

 these experiments are not sufficiently described. They were 

 <loubtless of very different degrees of fineness, and therefore 

 they were not of a kind to enable any just comparison to be 

 made between slag and superphosphate or any other manures. 



Professor Paul Wagner of Darmstadt has published in se]iarate 

 form the results of a very extensive series of experiments ^\T.th 

 the slag as a phosphatic manure for barley, wheat, and linseed, 

 "^rhc experiments were made in zinc boxes, and arranged so as 

 to exclude many of the accidents to which field experiments 

 are liable. The slag was ground to three dift'erent degrees of 

 fineness; No. 1 passed entirely through wire-cloth of 120 wires 

 per lineal inch : No. 2 was not (]uite so fine — 17 per cent, of it 

 refused to pass through the sieve ; and No. 3 was so coarse that 

 none of it passed through the sieve, but the half of it passed 

 through a sieve of 60 wires per inch, and the remainder all 

 passed through a sieve of 80 wires per inch. These samples of 

 slag were compared with coprolites as finely groimd as slag 

 No. 1, and with superph(wphate. 



Eijual weights were applied to all the boxes, and along with 

 the phosphates there were applied potash salts and nitrate of 

 soda in abundance. Superyihosphate produced the largest crop, 

 and if the superphosphate crop is put down as =100, the follow- 

 ing table shows the relative value of the forms of phosphate: — 



Superphosphate, 1"0 



Slag No. 1, 61 



Slag No. 2, 58 



Slag No. 3, 13 



( 'oprolite^, ....... 9 



The soil with which the bctxes were filled varied in different 

 series of boxes, — yiz., light sandy loam, calcareous loam, and 

 calcareous soil. The conclusion he draws from his experiments 

 is that, in order to compete with superphosphate, the finely 

 ground slag must be applied in double ({uantity. Had he 

 operated upon peaty or mossy soil or u])(jn stiff clay, he would 

 have obtained figures much more favourable to the slag, for 

 these are the soils upon which it has been found to produce 

 the best results ; and had he grown a crop M'hich is especially 

 benefited by the ap|)lication of phos]3hates and lime, such as 

 turnips or leguminous crojjs, it would have been a much better 

 test of the value of the manure. 



In Scotland we experimented upon turnips, and we used a 

 slag rich in })hosphoric acid, and ground to a fineness far greater 

 than that used by other experimenters, and we consequently 

 obtained results more favourable to the Thomas-slag than those 

 got elsewhere. It Avas found to be, weight for weight, superior 

 to su))erphosphate. 



