The American Journal of Pharmacy Volume 70 (Paperback)

This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1898 edition. Excerpt: ... the solubility of a substance is to make a saturated solution at the proper temperature and evaporate a weighed portion of the solution to dryness on a water-bath and complete the drying at a temperature of ioo C. or even higher in an air-bath. The higher this temperature and the more prolonged the heating, the smaller will be the quantity of the recovered substance and, hence, a decreased solubility is the result. To illustrate: the solubility of phenacetin is stated by different authorities to be one part phenacetin in 1,400, in 1,500, in 1,850 and in 2,000 parts of water, the temperature of which ranges from cold (?) to 200 C; these discordant statements are in all probability due to the volatility of the phenacetin. In the quantitative estimations, drying, after treatment with suitable solvents, is a necessary operation and, hence, the same results are to be looked for. While my experiments did not include higher temperatures than ioo C, the behavior of exalgin and acetanilid will be duplicated, without doubt, at somewhat higher temperatures by the less volatile methacetin, phenacetin and lactophenin. The difference in the behavior of acetanilid and of methacetin, phenacetin and lactophenin at temperatures below 850 C. suggested the possibility of detecting acetanilid in these other remedies. For this purpose I selected phenacetin as the substance which has the reputation of being adulterated at times with acetanilid; whereas methacetin and lactophenin, according to a criticism of my paper of two years ago, have not been known to be so adulterated, and, inferentially, my time wasted, in providing for such a contingency; 0025 gramme acetanilid was weighed in a watch-crystal, covered with 0475 gramme phenacetin (making a 5 per cent, ..