VOL. XC.] PHILOSOPHICAL TRANSACTIONS. 733 



that the degree of putrescibility in the various parts of animals, depends principally 

 on the presence, and on the quantity and quality, of gelatin; and the skin of the 

 rhinoceros found on the banks of the Vilui, near Yakutsk, was preserved, in all 

 probability, partly by the nature of the climate and soil, and partly by the superior 

 horny quality which it possessed over other skins; for it may be much questioned, 

 whether the hide of an ox or horse, in the same situation, would have escaped 

 putrefaction for so long a period*. 



From the preceding observations it appears, that gelatin is a component part of 

 many animal substances. That it differs in quality, from a very attenuated jelly or 

 mucilage, to that viscid substance called glue; the varieties of which also differ in 

 solubility and tenacity. That it is present in various proportions; so that certain 

 bodies, such as the cutis, and the cartilages of the joints, are formed by it; while 

 others, like nail, quill, and tortoise-shell, can scarcely be said to contain it. And 

 that, by its presence, in various states and proportions, it may be regarded, in- 

 cluding inherent moisture and organic arrangement, as the principal cause of those 

 degrees of flexibility, of elasticity, and of putrescibility, so various in the different 

 parts of animals-}-. But, when gelatin has been separated from the different sub- 

 stances, either by repeated boiling with water, or by being steeped in dilute acids, 

 a more insoluble substance remains, of a very different nature, which I shall now 

 proceed to examine. When a bone or piece of ivory has, by long boiling in water, 

 been deprived of a great part of its gelatin, and is afterwards steeped in a dilute 

 acid, the ossifying substance is dissolved, and the cartilage remains, retaining the 

 figure of the original bone; or, if a similar bone or piece of ivory, which has not 



* The more viscid gelatinous substances do not appear to be so immediately susceptible of putre- 

 faction as those of the opposite quality j for, when solutions in water of animal mucilage, eel-skin 

 glue, and strong glue, were during a certain time exposed under equal circumstances, I found the mu- 

 cilage to be the first, and the glue the last, which showed symptoms of putrefaction. f As gelatin, 



according to its proportion and quality, appears to produce considerable effects on the parts of animals 

 in which it is present: and, as the gelatin in animal bodies is, in all probability, liable to be changed 

 and modified by morbid causes, it is much to be wished, that gentlemen of the medical profession 

 would ascertain, by experiments, how far the tonic properties of barks depend on the tanning*principle. 

 Mr. Biggin has proved, (Phil. Trans, for 1799, p. 259,) that willow bark, and especially that of the 

 Huntingdon or Leicester willow, contains the tanning matter in a considerable quantity ; and that the 

 latter, in this respect, even equals, or rather exceeds, that of oak. My friend, the Rev. Thomas 

 Rackett, Rector of Spetisbury and Charlton, in Dorsetshire, has employed, in these parishes, the bark 

 of the common willow with great success, as a tonic and febrifuge. Also, Mr. Westring, of Norv- 

 koping, has observed, (Annales de Chimie, torn. 32, p. 179>) that those species of cinchona which 

 contain the tanning principle in the greatest quantity, are the most efficacious in fevers ; and that the 

 cinchona floiibunda, which contains scarcely any tanning matter, is destitute of the above-mentioned 

 beneficial effects. Mr. Westring therefore, with great apparent reason, believes that the relative effects 

 produced by the different species of cinchona, when employed in medicine, are in proportion to their 

 tanning power, or the quantity of tanning principle contained in them. If any one should be induced 

 to make experiments on the tonic effects of the tanning principle, it is to be hoped that some attention 

 would also be paid to the medicinal properties of nitro-muriate of tin, of which, at present, I believe 

 little or nothing is known. — Orig. 



