1823.] Philosophical Transactions^ Part 1. 1S12. 57 



position collected over mercury were carbonic and muriatic acid 

 gases,* and the volume Qf the latter was double that of the former, 



4. Phosgene gas is decomposed b}^ water, carbonic acid and 

 mmiatic acid being formed. 



5. Tin fused in the gas decomposes it; fuming liquor of 

 Libavius is formed; and carbonic oxide, equal in bulk to the 

 phosgene gas, remains. Zinc, antimony, and arsenic, heated 

 in tlie gas, produce the same effect. White oxide of zinc, and 

 protoxide of antimony, likewise, decompose it, 



6. Sulphur and phosphorus sublimed in the gas produced no 

 change. 



7. Mixed with hydrogen or oxygen singly, the mixture was 

 not inflamed by the electric spark ; but when the two gases were 

 mixed at once, in the proportion of two measures of hydrogen 

 and one of oxygen, a violent explosion was produced by electri- 

 city, and muriatic and carbonic acid gases were formed. 



Vn. A Narrative of the Eruption qf a Volcano in the Sea, off 

 the Island of St, Michael. By S. Tillard, Esq. Captain in the 

 Royal Navy. Captain Tillard, approaching the island of St, 

 Michael, one of the Azores, on the 12th of June, 1811, in the 

 sloop Sabrina, observed columns of smoke rising at a distance, 

 which were at first conceived to arise from two ships engaged at 

 sea. But it was soon observed to proceed from a volcano, which 

 had just broken out in the neighbourhood of St. Michael, 

 Captain Tillard and some other gentlemen next day crossed the 

 island of St. Michael, and witnessed the appearances of the 

 volcano for several hours. It was within a short mile of St, 

 Michael, and in a part of the sea formerly 25 fathoms deep. 

 While they surveyed it, a peak elevated itself above the sea, and 

 became very conspicuous before they left the place. About a 

 month after, the effects of the volcano had subsided; and an 

 island was formed, somewhat less than a mile in circumference. 

 Upon this island Capt. Tillard, and some of his officers, landed 

 with difficulty, and named it Sabrina. It consisted chiefly of a 

 narrow steep cliff surrounding a crater. This crater was full of sea 

 v/ater, boiling hot, and it emptied itself by the east side into the sea. 



VIIL On the Primitive Crystals of Carbonate of Lime, Bitter 

 Spar, and Iron Spar. By William Hyde Wollaston, M.D, 

 Sec. R. S. These three minerals, which differ essentially in 

 their composition; the first being composed of carbonic acid and 

 lime; the second of carbonic acid, lime, and magnesia; the 

 third of carbonic acid and oxide of iron ; had been conceived by 

 mineralogists to agree in their primitive form : and this agree- 



* This statement is somewhat obscure. We should ha'?e been told how the 

 decomposition was produced. It could not be by heat, because the salt sub- 

 limes without decomposition. It was probably by which combiued 

 TRTith the base and let the phosgejae gas liberty* 



