Chemistry and Physics. 275 



in weight of these two precipitates gave for the phosphoric acid 32*40 

 per cent. 



To the filtered solution from the phosphoric acid, was added caustic 

 potash in excess, and the whole boiled until the ammoniacal vapors 

 were effectually expelled, and the solution gave a strong alkaline reac- 

 tion. The magnesia thus obtained was collected upon a filter, washed 



with boiling water, incinerated and weighed ; it yielded magnesia 14-45 

 per cent. - 



Another portion of the powdered concretion dried over sulphuric 

 acid in vacuo at ordinary temperatures, yielded hygrometric moisture, 1 

 per cent.; incinerated, it yielded volatile matter (water and ammonia), 

 51*70 per cent. 



In order to ascertain the amount of ammonia, another portion of the 

 powder was introduced into a small tubulated retort, with carbonate 

 of soda and water. The neck of the retort was adapted to a small 

 tubulated receiver containing dilute hydrochloric acid, and having 

 adapted to its tubulure a nitrogen bulb, such as is used in ultimate or- 

 ganic analysis; this also contained dilute hydrochloric acid. The 

 fixture in the retort was evaporated to dryness ; and at the close of 

 the operation, air was drawn through the apparatus to insure the ab- 

 sorption of the last portion of ammonia. The ammonia thus obtained 

 was estimated by precipitation by chlorid of platinum, as in organic 

 analysis, and yielded 07 1 per cent. 



Hence the composition of the concretion is as follows : — phosphoric 

 acid 32-40 per cent., magnesia 14*45, water 50-35, ammonia '71, insol- 

 uble inorganic matter -45, insoluble organic matter -64, hygroscopic 

 moisture 1-00=100-00. 



It will be seen from this, that the ammonia is too small to be consid- 

 ered an essential ingredient of the concretion. Assuming it to exist 

 nJ^ e State °f double phosphate of ammonia and magnesia with water 

 (NH±0, 2MgO, PO 5 +2HO+10HO), and deducting the amount of 

 l nis salt from the rest, (omitting the insoluble matter and hygroscopic 

 Moisture,) it will be seen that the concretion is composed mainly of the 

 phosphate of magnesia and water, according to the following formula, 

 dM gO-f3HO-f2P0 5 -f24 aqua, as will be seen from the following 

 comparison : 



By Experiment. % Calculation 



Phos.acid, 33-56 - - 2PO*, 3370 

 Maanesia, 14-55 - - - 3MgO, 15-20 



WaW, 51-89 - - 24Aq. 5110 



foOQO 1000 ° 



20- Acetate of Lime formed in Coal Pits, (Proc. Amer. Phil. Soc., 



j a "-, 1846, iv, p. 239.)— Dr. Boy e stated that by a visit to Colemanville 



ron Works, Lancaster County, Pa., he had found on the outer surface 



of the coal pits for charring wood, a yellowish white deposition. 



.. 0n examining this deposition, it was found to consist of acetate of 



l^e. By dissolving it in water and treating it with animal charcoal, 



the acetate of lime was obtained perfectly colorless. Dr. Boye remark- 



p that the lime was probably derived from the soil, but as acetate of 



ltn e was not volatile, it must be carried up mechanically by the vapors 



