264 
BRITISH PHARMACEUTICAL CONFERENCE. 
almost entirely free from codeia, as was also tlie mother-liquor from which 
they had been precipitated. 
On a review of these experiments, it will be observed that the three sam¬ 
ples of hydrochloratc of morphia contained varying proportions of water, and 
varying quantities of the alkaloid in like proportion,—that which was the 
least soluble, No. 1, having the largest proportion of the alkaloid, that which 
was most so, containing the largest proportion of water, as in No. 3 ; the dif¬ 
ference between No. 1 and No. 3 being equal to nearly five per cent, of water, 
and nearly live and a half per cent, of alkaloid. The codeia appeared in 
each specimen to have been carefully separated. The range of moisture in 
the acetate was a little wider than in the hydrochlorate, the loss in No. 1 be¬ 
ing live per cent., whilst that in No. 3 was about twelve and a half per cent. 
I regret that I have not been able to carry out this investigation to the 
extent that I had proposed and wished, but should I be again permitted to 
furnish a paper to the Conference, I hope to devote more attention, and to 
direct my observations more usefully. 
ON COMMERCIAL PHOSPHORIC ACID. 
BY R. PARKINSON, PH.D. 
(Read at the Bath Meeting of the British Pharmaceutical Conference , Sept. 1864.) 
What is the quality of the diluted phosphoric acid met with in commerce, 
and what the best and safest method of obtaining it of constant strength ? is 
the question to which I have undertaken to devote some attention. The 
quality I take to mean firstly strength, inasmuch as this is an article not 
generally likely to be much adulterated, except with water, and secondly the 
presence of foreign substances in it, among which meta- and pyrophosplioric 
acids may be included. From my provincial position and general close confine¬ 
ment to home, I have been unable to make a properly representative collec¬ 
tion. I have however through the kindness of friends obtained and examined 
about thirty samples, twelve or thirteen of which were collected for me from 
wholesale and dispensing houses in London and neighbourhood, by Dr. 
Attfielcl, and the remainder are from towns in Yorkshire, Lancashire, Cheshire, 
and one from Cumberland. I have arranged the results in the form of a 
table, giving the percentage of acid, the specific gravity, and other remarks 
where necessary; and I have placed at the head of the list, for standards of 
comparison, the percentage and specific gravity of the acids of the British 
and London Pharmacopoeias respectively. It will be seen that only three of 
the specimens come up to the B. P. standard, two more are considerably above 
P. L., then again three may be regarded as sufficiently near P. L., and the 
remaining twenty are of various shades of declension. I have observed in 
some cases a discrepancy between the specific gravity and the percentage 
amount, for which I cannot account. I have re-examined some of the more 
glaring ones, but could arrive at no other result, and had not time to go 
through them all again. The specific gravities were all taken consecutively 
and at a different time from the percentages, which were estimated by the 
volumetric method with nitrate of uranium, originated by Mr. Sutton. In 
those samples, which are made from glacial phosphoric acid, and which con¬ 
tain phosphate of ammonia, the percentages will not represent the free acid, 
but the total amount both free and combined. I have been unable to devise 
a satisfactory method for readily ascertaining the amount of free acid. The 
ordinary plans of acidimetry will not do, as may be known, when it is con¬ 
sidered that the chemically neutral phosphates have an alkaline reaction. 
