386 ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



perimerits upon the conversion of the tribasic phosphates 

 into a more soluble modification showed that sulphuric acid, 

 by itself, was not adapted to the purpose, since not only the 

 quantity of soluble phosphates formed was small in compar- 

 ison with the amount of acid employed, while the nitrogen 

 was reduced, but the resulting product had a tendency to 

 become moist and form a doughy mass, unsuitable for a 

 solid manure. By treating the guano first, however, with 

 alkalies, and then with sulphuric acid, a most excellent pot- 

 ash manure was obtained, the employment of which, how- 

 ever, could only be profitable, under peculiar circumstances, 

 where caustic alkalies are cheap. 14 (7, CCXV., 1875, 460. 



DETERIORATION OF SUPERPHOSPHATES WITH AGE. 



Millot, in a recent communication, confirms his previous 

 conclusion that the gradual decrease of soluble phosphoric 

 acid in superphosphates, even with excess of sulphuric acid, 

 is due to the formation of jDeculiar phosjmates of alumina 

 and iron. He states that, while all the phosphoric acid in 

 a superphosphate manufactured from coprolites of the Ar- 

 dennes is soluble immediately after its preparation, only 10 

 per cent, of the whole amount remained soluble after two 

 years. After extracting it with hot water, until all the gyp- 

 sum was removed, no lime was found in the residue, but the 

 new compounds of iron and phosphoric acid Fe 2 3 , 2P0 5 , 

 and 2Fe 2 3 , 3PO,,. Alumina plays precisely the same part 

 as the sesquioxide of iron, except that its phosphates are 

 more soluble than the corresponding iron compounds. The 

 use of phosphates of iron and alumina as fertilizers, there- 

 fore, seems rather unadvisable. 14 (7, CCXVL, 1875, 92. 



NEW MINERAL MANURE. 



A substance has recently been offered in France as a val- 

 uable mineral manure. It is in the form of a bituminous 

 slate of the lias formation in a finely powdered condition. 

 This is prepared by M. A. Belenet, according to whom it con- 

 tains about 20 per cent, of lime, 2 of soda and potassa, 1 of 

 sulphur, 4 of mineral oil, and J per cent, of phosphoric acid, 

 chlorine, and magnesia, with a trace of carbonate of iron and 

 lignite. According to the inventor, this bituminous slate 

 acts in a double way upon plants: first by its soluble chem- 



