o^O Experimenls and Ob/e^-vaiions 



Some experiments on cartilaginous fubftances (which T 

 intended to have inferted in this paper, but which I am 

 prevented from doing, as they are not as yet fufficiently ad- 

 vanced) have in a great meafure convinced me, that mem- 

 branes and cartilages (whether deflined to become bones by 

 a natural procefs, as in young animals, or whether they be- 

 come fuch by morbid offification, as often happens in thofe 

 which are aged) do not contain the offifying fubftance, or 

 phofphat of lime, as a conftituent principle. I mean by 

 this, that I believe the portion of phofphat of lime, found in 

 cartilaginous and horny fubftances, to be fimply mixed as an 

 extraneous matter; and that, when it is abfent, membrane, 

 cartilage, and horn, are moft perfeft and complete. 



The frequent prefence of phofphat of lime in cartilaginous 

 fubftances, is not a proof of its being one of their conftituent 

 principles, but only that it has become depofited and mixed 

 with them in proportion to the tendency they may have to 

 form modifications of bone, or according to their vicinity 

 with fuch membranes or cartilages as are liable to fuch a 

 change. If horns are examined, few, I believe, will be found 

 to contain phofphat of lime in fuch a proportion as to be 

 confidered an eflential ingredient. I would not be under- 

 ftood to fpeak here of fuch as flag or buck-horn, for that 

 has every chemical character of bone, with fome excefs of 

 cartilage; but I allude to thofe in which the fubftance of the 

 horn is diftinftly feparate from the bone, and which, like a 

 Iheath, covers a bony protuberance which ifl'ues from the 

 OS frontis of certain animals*. 



Horns of this nature, fuch as thofe of the ox, the ram, 

 and the chamois, alio tortoife-flTell, afford, after diftillatioa 

 and incineration, fo very fmall a refiduum, of which only a 

 imali part is phofphat of lime, that this latter can fcarcely be 

 regarded as a neceflary ingredient. 



By fome experiments- made on 500 grains of the horn of 

 the ox, I obtained, after a long continued heat, only 1,50 

 grains of refiduam ; and of this lefs than half proved to be 

 phofphat of lime. 



♦ Nature feems here to Kave made an analyfis, or reparation of horn 

 from bone, 



^8 Grains 



