154 Scientific Intelligence, [Feb. 



only no direct emanation from the sun, but even the diff'use light was 

 rendered much feebler than common bv a thick snow-storm, which had 

 covered the skylight above with a thick mantle, and veiled the heavens 

 in a singular degree for such a storm. Under these circumstances, 

 the hydrogen vvms scarcely all introduced before the flask exploded 

 irith a distinct flame ; portions of the glass stuck in the woodwork of 

 the ceiling of the room, and the face and eyes escaped by being out of 

 the direction of the explosion ; nothing but the neck of the flask 

 remained in hand. This occurrence then proves, that a mixture 

 of chlorine and hydrogen gas may explode spontaneously in a 

 diffuse light, and even in a very dim light." — (American Journal of 

 Science, Vol. 3, No. 2, p. 34-3.) 



VI. Sidphato-tricarhonate of Lend, 



A very fine specimen of carbonate of lead was recently brought 

 from Leadhills, by Alexander Irving, Esq. who found it by analysis to 

 be a sulphato-carbonate. Upon examining its crystals, I find it to be 

 the sulphato-tricarbonate of Mr, Brooke. The crystals, which are of 

 considerable size, are acute rhomboids, with cleavages perpendicular 

 to the axis of the rhomb. They are of a bright sap-green colour. 

 Upon examining their optical structure, I find that they have two axes 

 of double refraction, the principal one of which is coincident with the 

 axis of the rhomb. The sulphato-tricarbonate, therefore, cannot have 

 the acute rhomboid for its primitive form, but must belong to the pris- 

 matic system of Mohs. D. B. — Edin. Phil. Jour. 



VII. Calc-sinter determined to be true Calcareous Spar. 



The Rev. Dr. Fleming, of Flisk, transmitted to me lately two speci- 

 mens of this substance, with the following remark : " Lamellar calc- 

 sinter from Macalister's Cave in Sky. I procured these crystals in 

 shallow pools in the cave filled with the calcareous water. The indi- 

 cations of crystallization are distinct, but the crystals seem to be but in 

 progress. The summits of the crystals of the smallest piece are smooth 

 and flat, and indicate the prisms below to be five-sided, and sometimes 

 four-sided. I regard these specimens as exceedingly curious, as they 

 are genuine examples of Neptunian calcareous spar 2. Acicularly 

 Crystallized fibrous Calc-sinter. — This substance is from the Isle of 

 Man ; the specimen from which these fragments were separated was 

 given me by Mr. Stevenson several years ago, and is interesting as 

 being a recent aqueous formation." Dr. Fleming adds, '* that all the 

 calcareous matter in Macalister's Cave, whatever be its external form, 

 stalactitic, stalagmitic, or encrusting, is all more or less in the state of 

 calcareous spar, with the usually foliated structure : that which lies in 

 the pools or hollows of the caves has its crystalline forms like those in 

 the specimens sent." Upon examining these interesting specimens, I 

 succeeded in extracting from them regular rhombs of calcareous spar, 

 having their angles of the same value as the finest specimens of carbon- 

 ate of lime. Their double refraction and their polarising force, were 

 of the same character and the same intensity as the purest Iceland 

 spar. D. B.—(Edin. Phil. Jour.) 



VIII. New Mineral from Aachen ^ near Altenberg, 

 Having examined a very fine crystal of Stilbite from Aachen, near 



