54 



Tlie result of tlie analysis, given under i. and ii., shows 

 the composition of the specimen after deducting the insoluble 

 residue, and No. in. is the percentage composition calculated 

 from the formula 9 Cug S + 2 (FeSg, l^eS), and from these 

 it will be seen that the above formula represents the composition 

 of the Moonta Mine mineral : — 



100-55 100-00 100-00 



Analysis of a Quartz Eock from Brougiitox Extension. 



This rock occurs in pieces of all sizes scattered over the hill- 

 side at the above named place, and the analysis was made with 

 the view of comparing its composition with that of the so-called 

 Dinas clay of the Yale of Neath, Wales, which in appearance it 

 very much resembles. 



No. I. is the analysis of the rock in question, and No. ir. 

 shows the composition of the Dinas clay as given by Percy: — 



100-66 99.49 



It will be seen from the above analysis that in all essential 

 respects this rock corresponds in constitution with that of the 

 Dinas clay. 



Analysts of a Boiler Deposit. 

 1)1 connection with mineralogical chemistry the question of 

 the composition of the mine water of this district is of con- 

 siderable interest. It is probably within the knowledge of the 

 fellows of this Society that the water which finds its way into 

 the mines on Yorke's Peninsula is salt, and even at the lowest 

 depths this character of the water still holds good. I have not 

 had occasion to make an examination of the water, but, as 

 bearing upon the subject, I subjoin the result of the analysis 

 of a boiler deposit obtained from one of the boilers on the 

 Wallaroo mine, which was fed with the water pumped from the 

 mine. As I received it the deposit was in the form of a fiue 



