Mineralogy and Geology. id 123 
three atoms of base to one atom of acid), with the difference that in the 
exterior layer the three atoms of base are made up by lime alone, thus 
forming the so-called tri-phosphate of lime, whilst in.the body of the rock 
only two of them are lime and the third is water, a combination which 
is known as common phosphate of lime. ; ’ 
In the following we add a few items which may prove the correctness 
of this view: 
(1.) Common phosphate of lime, when exposed toa high degree of tem- 
as that portion conveyed to it by the atmosphere, necessarily came in 
peculiar state 
that in terior ic acid is present in the form of sul- 
Phate fine widet te sod of the rock contains it as sulphate of lime. 
4. Chemical Analysis and Comparison of Serpentine Marbles 
erd Antique; by Cuarzes T. Jackson. (Read “o 
fore the Boston Society of Natural History, February 20th, aay ~ 
Having made the original geological surveys of the great masses me 
