11. Antiseptic vegetables yield tinctures to lime water, which resist putrefaction more powerfully than those prepared from the same drugs with distilled water, without lessening the cohesion of animal fibres. 12. Waters which contain a large quantity of calcareous earth, either simply suspended, or in a neutralized state, are highly improper for pharmaceutical purposes in general, and especially for the preparation of extracts, where much water and long continued boiling are requisite. 13. The power of fixed air to restore sweetness to putrid bodies, is, it is hoped, clearly established: and there appears to be some degree of probability, that fixed air produces this effect by acting as a menstruum to the putrid effluvia: It seems also to be proved, that its antiseptic quality is not owing to any acidity which it carries off with it from the effervescing mixture. _THE END._ [Illustration: Decorative Band] AN APPENDIX TO Experiments and Observations On the PREPARATION of MAGNESIA, &c. CONTAINING Strictures on Mr. GLASS'S MAGNESIA. By THOMAS HENRY, Apothecary. Manchester, March 8, 1773. IT is with the utmost reluctance I find myself indispensibly obliged to address the public on a subject, from the nature of which I may perhaps incur the suspicion of acting from interested views: should I be so unhappy, my friends who know me will, I trust, do me the justice to acquit me of the charge of being influenced by any improper motives; and I shall hope for the candid indulgence of those persons to whom I am a stranger. About a year and half since I transmitted to the College of Physicians an account of a method of preparing Magnesia Alba, equal to that which had been long sold by Mr. Glass of Oxford, and which was generally and deservedly esteemed by others, as well as by myself, to be the standard of purity. Though that gentleman carefully concealed the minutiæ on which the success of his process depended, he had always prepared it with the most laudable attention. My process was received by the College, and published in the second volume of the Transactions of that truly respectable society, and has since been reprinted in a pamphlet which I lately published, and in which, among other subjects, I have recommended Calcined Magnesia to the attention of the faculty, as a medicine of considerable importance. Notwithstanding I had been informed, by a relation of Mr. Glass, that he had disposed of his name in the Magnesia business to some persons, for a very valuable consideration, yet I doubted not their adhering to the proper manner of preparing it; but as I have since had occasion to change my opinion, and as the credit of the Calcined Magnesia depends so much on its purity before calcination, I am necessitated to take this method of informing the public of my reasons for declaring that sold under the name of Mr. Glass to be impure, calcareous, and improper for the purpose of calcining.