3f>i DefcrlpUon of an Air and a iVater-Vault. 



one of the mofl. eflential parts has been taken away. Now 

 fiich foffil or burned bones can no more be regarded as 

 bone, than charcoal can be confidered as the vegetable of 

 which it retains the figure and fibrous ftrufture. 



J3ones which keep their figure after combufiion refenible 

 charcoal made from vegetables replete with fibre ; and car- 

 tilaginous bones which lofe their (liape by the fame caufe 

 may be compared to fucculent plants, which are reduced in 

 bulk and fhape in a fimilar manner. 



From thefe laft experiments I much queftion if bodies 

 confifting of phofphat of lime, like bones, have concurred 

 materially to form ftrata of linieftone or chalk ; for it appears 

 to be improbable that phofphat is converted into carbonat of 

 lime after thefe bodies have become extraneous fofiRls. 



The dcftruftion or decompofition of the cartilaginous parts 

 of teeth and bones in a foffil ftate muft have been the work 

 of a very long period of time, unlefs accelerated by the adlioa 

 of fome mineral principle j for, after having, in the ufual 

 manner, fteeped in muriatic acid the os humeri of a man 

 brought from Hythe in Kent, and faid to have been taken 

 from a Saxon tomb, I found the remaining cartilage nearly 

 as complete as that of a recent bone. The difficult dcftruc- 

 tibility of fubftances of a fomewhat fimilar nature appears 

 alfo from the piercing implements formed of horn, which 

 are not unfrequently found in excavations of high antiquity. 



XI. Dcfcription of an Air and d JValer-Vinilt employed fo 

 equalize the difcharge of Air into a Blajl-Furnace. By 

 Mr. David Mushet. 



X^ IG. I. (Plate XI.) reprcfents a vertical fedion of the ele- 

 vation of an air-vault 60 feet long and 30 feet wide, confifting 

 of four arches of regularly progrcffive fizes. This building is 

 fcnerallv conftruded under the bridgehoufe, where the ma- 

 terials are daily coUetiled for filling the furnace. AB, repre- 

 fents the acclivity to the furnace top. The fpace betwixt 

 the aTch-tops and the level of the floor is filled with mate- 

 rials as denfc as can be procured. The walls of the under 



part 



