Ii6 An Attempt to make a Thermometer , See. 
ot earthy bodies, they afford the fulleft evidence which the 
nature of the fubjed can admit of, that die indiffolubie part 
of this clay is truly filiceous ; and confequently that the clay 
confiffs of two parts of pure filiceous .earth, to three parts of 
pure argillaceous or aluminous earth. 
