204 



PROCEEa)INGS OF SOCIETIES. 



Mr. Butler's experiments led up to the same results as those which 

 had been arrived at by Mr. Hartley. At the time his own experi- 

 ments were made, it was not known that liquid cai-bonic acid occupied 

 any place in the mineral world ; but from the conclusive observations 

 which had been made since that date, they could not now doubt its 

 existence there as a natural product. Mr. Hartley had enjoyed the 

 advantage of the experiments of Professor Andrews upon the subject, 

 which of course he (the President) had not the opportunity of referring 

 to at the time his own experiments were made. At the present time 

 an observer knew exactly what to look for, and they knew very well 

 how much more easy it was to find a thing when we knew just 

 exactly what it was that we ought to look for. Some of the effects 

 which had been mentioned by Mr. Hartley were very remarkable ; the 

 peculiar effect at the time of boiling was very so, but then it was 

 so quickly done and the changes took place so rapidly that it was 

 quite a matter of astonishment to anyone seeing the experiment for 

 the first time. In sapphires he could never detect any water in the 

 cavities ; they ai)peared in all cases to be filled purely with carbonic 

 acid ; and he believed that it was a fact that the sapphire was always 

 found in connection with limestone. Any gentleman who had not yet 

 seen these effects would be very much sur^jrised at them. In their 

 bearing upon theoretical geology they were of coiu'se of very great 

 importance. 



Mr. Hartley said he had observed in the case of nearly all 

 his specimens that the surface of the fluid in the cavities had a 

 concave curvature, showing that the sides were wet, and thus in- 

 dicating the presence of water as well as carbonic acid ; but in the 

 specimens of sapphire the curvature of the surface of the contained 

 fluid was convex, and the sides seemed to be jierfectly dry, from which 

 he judged that the fluid in these instances was pure carbonic acid. 



The President said that it gave him much pleasure to announce 

 that Mr. Butler had kindly promised to exhibit his specimens at their 

 aiDproaching conversazione. Mr. Hartley also signified his willingness 

 to exhibit his apparatus, &c., on that occasion. 



Mr. Eutley mentioned that the President had referred to the 

 circumstance of the sapjihire being usually found in limestone ; there 

 was, however, an instance occurring in some mines in Carolina, U.S.A., 

 in which corundum occurred in gneissic rock. 



The President said that the cavities were very rare in the case of 

 the ruby ; Mr. Butler had only found one or two specimens containing 

 liquid, out of many hundreds which he had examined. 



The Secretary said they had received a paper from Mr. Dallinger, 

 one of their Vice-Presidents, " On a New Arrangement for Illuminating 

 and Centering with High Powers." The paper was too technical to 

 be readily understood unless it were in the hands of every Fellow. 

 Mr. Dallinger had found that the precise position of the lamp was of 

 great importance as well as the exact centering of the illuminating 

 ajiparatus, and he had devised a lamp for the purpose with a screw 

 motion, by means of which the exact position required could be 

 obtained. The paper without the diagrams would, he feared, be quite 

 unintelligible to the meeting ; it would therefore be " taken as read," 



