Dr Anderson's Analysis of Caporcianite, 8fc. 21 



tion through so considerable a depth, that the winter wave of 

 cold (consisting of many diurnal waves of alternate, greater 

 and less intensity) may not travel do^vn to the adit or cavern 

 till the hottest period of the next summer, or of many sum- 

 mers ; in short, that if at any given time the interior of the 

 mountain were sounded by thermometers down its whole axis, 

 these instruments would exhibit alternate deviations + and 

 — from the mean temperature of the air. 



Analysis of Caporcianite and PhakoUte, two new Minerals of 

 the Zeolite Family. By Thomas Anderson, M.D. Com- 

 municated by Dr Christison.* 



The minerals of the zeolite family have for many years attracted the 

 especial attention of men of science, and the class has been rapidly ex- 

 tended in proportion to the progress made in its study in a crystallogra- 

 phic as well as chemical point of view. The first characteristic difi'erence, 

 originally observed long since by Cronstcdt, and by him considered to 

 be the distinguishing mark of one single mineral species, which he de- 

 signated Zeolite, — namely, the property of swelling out by heat previous 

 to fusion, — has since been found to belong to a great number of other com- 

 binations. These, although materially diiFerent from each other in crys- 

 tallographic form, have proved to be closely allied in chemical constitu- 

 tion, in so far as they consist, without exception, of a silicate of an alkali 

 or alkaline earth in combination with a silicate of alumina and water. 

 It is evident, then, that the relation of the silicic acid to the base, in both 

 terms, as well as the quantity of water, is capable of considerable varia- 

 tion, so that the general mineraloglcal formula which should embrace 

 all the members of the zeolite family would be 



u r S" + J.- A Sy + z A ?. 

 AVTiere r represents the monatomic alkaline or earthy basis, and the 

 terms u, v, x, y, and z, are capable of varying within certain limits. 



The minerals Caporcianite and Phakolite form two new members of 

 the above general formula. Their analysis was conducted in the follow- 

 ing manner : — 



The finely pulverized mineral was dried for several days over sulphuric 

 acid in an exsiccator, at the ordinary temperature of the atmosphere. A 

 certain quantity of the dry powder was then weighed in a small tube 

 retort, and heated to moderate redness for the space of half an hour. The 

 water thus driven off was absorbed in a counterpoised tube of chloride 



» Read before the Royal Society of Edinburgh on April 18. 1842, and 

 published in part 2, vol. xv. of the Transactions. 



