62 HOW ON LIMESTONE AND MARBLE. 



geological survey. Limestones fit for making lime for manure are 

 those which are nearly pure carbonate of lime. I have heard it ob- 

 jected to the use of Windsor lime as a manure that it contains mag- 

 nesia in large quantity ; this is certainly not the case with that 

 obtained from the rock on the property of O. King, Esq., for w^hen 

 I made an analysis of a specimen of that found on the bank of the 

 Avon behind his house, it gave me : 



Carbonate of Lime, 97.64 



Carbonate of Magnesia, L 1 



Oxide of Iron, .07 



Clay, sand and silica, 0,68 



Phosphoric Acid, traces 



99.49 



results which show that there is but little magnesia in it, even for 

 an ordinary lime ; for the sake of comparison I may state that in 

 Professor Anderson's ^'Elements of Agricultural Chemistry,^'' the 

 analyses of two common limestones are given as examples of the 

 composition of these rocks, and 1.61 and 7.45 are the respective 

 percentages of carbonate of magnesia. 



As many limestones of the Province, like that of which the ana- 

 lysis has just been given, are chiefly made up of the shells of molhisca 

 it will not be out of place here to give an unpublished analysis* of a 

 recent shell made many years ago ; the cleaned shell of the Peri- 

 winkle {Litorina litorea), gave 



Carbonate of Lime, 97.175 



Sulphate of Lime, .479 



Organic Matter, 2.010 



Phosphoric Acid, 0.001 



Silica and Sand 0.164 



99.829 



whence it appears that there is not a great difference between the 

 composition of the recent shell and the rock which, many hundreds 

 of thousands of years ago probably, was to a great extent made of 

 the remains of the shells of allied animals. 



^Published with others since this paper was read, in Silliman's Journal of 

 Science, May, 1866. 



