On the Mineral Cyprusite, By Julien Behy. 189 



invisible to the naked eye, consist of the skeletons of marine, 

 polycistins (Eadiolaria) in a tolerable state of preservation, along 

 with many smaller debris of the same, as also of a few sponge 

 spicules, but I could discover no diatoms among them. 



The cyprusite polycistins belong principally to the group com- 

 prising the Heliosphxridse, but a curious elongate conical form of 

 a Polycyrtida is not uncommon in the deposit as well as repre- 

 sentatives of some other families. The insoluble residue of the 

 mineral after treatment by acids consists almost entirely of these 

 organic remains. Ehrenberg's and Haeckel's works not being at 

 my disposal at my present residence in Spain, I cannot determine 

 the species nor even the genera of these Eadiolaria, nor can I 

 establish if these forms are still living in the present surrounding 

 seas. I must, in consequence, leave this work for others better 

 situated, and to whom I will be glad to communicate the necessary 

 material on application. 



One thing is certain, namely, that at one time or another, the 

 cyprusite beds must have existed under the level of the sea. 



The origin of the cyprusite is a subject of some difficulty, and 

 lies, to a certain extent, within the realms of scientific speculation. 

 Its chemical production, as well as its geological genesis, may, 

 however, I believe, be explained theoretically by reference to the 

 following considerations : — 



It is weU known that a solution of a ferrous sulphate, exposed 

 to the air, undergoes oxidation. According to F. Muck,* in the 

 earlier stages of the oxidation, the solution contains normal ferric 

 sulphate Fca O3 . 3 SO3, and even free sulphuric acid, but ultimately 

 the basic salt Foa O3 . 2 SO3 distinguished by its deep brown colour. 

 At the same time the deposit becomes progressively richer in acid, 

 without, however, attaining the composition 2 Fcg O3 . 3 SO3 assigned 

 to it by Wittstein.f 



The products of the oxidation vary with the continually changing 

 composition of the solution, and cannot therefore be reduced to any 

 simple expression. As a rule, ferric sulphates, occurring as natural 

 products, are partly precipitates of this kind, and partly dried up 

 mother-liquors. 



The tribasie ferric sulphate Fca O3 . SO3 = Fcg (804)3 2 Fca O3 

 is produced artificially as a reddish yellow powder, containing about 

 3 at. water, by dissolving the basic double salts of potassic sulphate 

 and sesquibasic ferric sulphate in water, and heating the solution 

 (Soubeiran). 



If potash or soda be added to a concentrated solution of ferric 

 sulphate till the precipitate no longer redissolves, the filtered solu- 



* Jom-n. Pr, Chem., xcix. p. 103 ; Jahiesb. 1866, p. 241. 



t Rep. PhaiTu. [3] i. p. 185. . 



