MEDICINAL PHOSPHORIC ACID, 127 
ART. XVIII. — MEDICINAL PHOSPHORIC ACID. 
Mr. Vakenroder gives the preference in the preparation 
of Medicinal Phosphoric Acid to a process already known, 
but which he has modified, both in relative proportions and 
manner of manipulation. He mixes 200 grammesof calcined 
bones, reduced to fine powder, with 1300 parts of water, 
adds 150 grammes of concentrated sulphuric acid, diluted 
with 200 grammes of water, and after twelve hoursof contact in 
thecold, he digests the whole, at a gentle heat, for half an hour, 
replacing the water as it evaporates. He then strains with 
expression, and washes the residuum with 200 grammes of 
water. He then filters and passes through the liquid, a cur- 
rent of sulphuretted hydrogen ; then filters again, and evapo- 
rates, until only 160 grammes of liquid remain, and adds to 
this 320 grammes of alcohol, at 84 C. At the end of twen- 
ty-four hours he passes it again over the filter, and washes 
the acid phosphate of lime remaining upon the filter, with a 
new portion of alcohol, (30 parts.) He then distils, tore- 
cover the alcohol, and goes on with the evaporation, until the 
liquid weighs only 36 grammes, then dilutes it with sufficient 
water to make 120 grammes, adds a little vegetable charcoal, 
digests it for a little while, filters, and lastly concentrates the 
acid. 
Phosphoric acid thus prepared, still contains, as Mr. V. is 
convinced, a little acid phosphate of lime, but is suffi- 
ciently pure for medicinal use. He thinks, that by a new 
precipitation with alcohol, it might be obtained perfectly 
pure. A. D. 
Journ. de Pharm. 
