282 Annual Report of the Consultiiu/ Chemist. 



dust, and guano, which were sent for analysis in 1873 were all 

 genuine. 



The quality of Peruvian guano in 1873, in comparison with 

 that of the supplies of 1872, has neither improved nor deterio- 

 rated. Most samples of Peruvian Government guano, although 

 of good quality, and yielding an average of 11 to 12 per cent, of 

 ammonia, are too wet and lumpy to be distributed uniformly and 

 readily on the land. 



Occasionally dark, brown-coloured, sulphate of ammonia, 

 obtained in the purification of coal-gas, finds its way into 

 commerce. Most of these brown-coloured samples, I find, 

 contain appreciable quantities of sulpho-cyanide of ammonium 

 — -a salt which exerts a most pernicious influence upon vege- 

 tation, even if it is applied to the land in very small quantities. 

 Some preliminary experiments which I have made, with a view 

 of testing practically the effects of sulpho-cyanide of ammonium 

 upon plants, have shown me that it is the most powerful 

 poison to wheat, barley, and cereal crops with which I am 

 acquainted ; and I am inclined to think that as little as 10 lbs. 

 per acre of sulpho-cyanide of ammonium, in a top-dressing of 

 sulphate of ammonia, will injuriously affect the young barley 

 or wheat crop. The same and similar poisonous cyanogen 

 compounds occur not unfrequently in gas-lime and other 

 refuse materials obtained from gasworks, and used occasionally 

 for inanuring purposes. To my knowledge, great mischief some- 

 times is done by applying certain refuse materials from gas- 

 works to grass-land ; and I ain inclined to thinJc that the cause ol 

 the mischief may be traced, in perhaps not a few cases, to the 

 cyanogen compounds which occur in some refuse materials from 

 gasworks. 



I would therefore recommend great caution in the application 

 to the land of waste products from gasworks, and suggest that 

 such products should be carefully examined for cyanogen com- 

 pounds before they are used for manuring purposes. 



The supply of phosphatic minerals, from which the bulk of 

 artificial manures is prepared, has sustained no check in 1873. 

 New beds of phosphatic minerals are being discovered in all 

 parts of the world, and there is no danger that the manufacture of 

 artificial manures will suffer from want of raw phosphatic mate- 

 rials. One of the more recent discoveries of phosphatic minerals 

 has been made in the South of France, from whence we have 

 obtained, during the last year or two, rich mineral phosphates. 

 The following analysis is mentioned in illustration of the 

 character of the richer samples of French phosphate : — 



