[ 549 1 



liquid form. As some of the gases are dangerous to health 

 this condensing of the gases or vapours passing out is very 

 necessary. The gas given off is chiefly CO 2 , but HF, Sip4 and 

 Iodine vapour are also given off. As the acid is gradually let 

 into the powdered mineral a strong shaft provided with rakes 

 keeps the powder continually agitated. When the proportional 

 quantity of acid has been used up and the mixing completed 

 the contents of the chamber (which is usually 4 a ton to i ton) 

 is allowed to fall into a brick or stone-ware chamber known 

 as the "den," which when full is closed and allowed to remain 

 there until its temperature is reduced, the rise of temperature 

 being due to the mixing of the phosphates with the acid. 



897. The contents of the 'den' are afterwards dug out and 

 passed through a 'disintegrator' which renders the manure into 

 a powdery condition in which state it is sold. Unless sulphuric 

 acid can be manufactured on the premises in a super factory, 

 it does not pay to make super. The question of using super 

 in this country is beyond the pale of practical agriculture, if 

 sulphuric acid has to be purchased. But a sulphuric acid 

 manufactory can profitably make super as well, if a market 

 for this manure can be created, say among European planters, 

 Super manufacturing has been actually commenced in one 

 of the islands of the Malay Archipelago, where phosphatic 

 deposits of great purity have been discovered. Messrs. T. 

 Stanes & Co. of Coimbatore also manufacture and supply 

 super and other concentrated manures. 



898. Super is usually mixed with blood, soot and refuse 

 vegetable and animal matter of all kinds or with NaNOs or 

 (NH 4 )2 SCXi to convert it into a general manure. The composi- 

 tion of super varies very much according to the mineral used 

 in its manufacture. Oxide of iron> aluminium and magnesium 

 and free phosphoric acid (HsPCXt) are almost always present, 

 The whole of the bone or mineral is scarcely ever acted upon 

 by the acid. Ordinarily super contains- 25 to 28 per cent, 

 of soluble phosphates, but it is possible to have super with as 



