VOL. LXVI.] PHILOSOPHICAL TEANSACTIONS. 21 



it SO as to liquify the mixture, and removed both the thermometers into it; but 

 found the standard thermometer, viz. the instrument graduated by Messrs. 

 Nairne and Bkmt, London, had risen in the removal to 110° below O. As the 

 mixture in this 2d cup did not cover the bulbs, he added more as before, and 

 also poured some out of the tirst cup. The spare tube, graduated by himself, 

 stood in this cup at 130°; but the standard fell deliberately to 263, where it stood 

 again. He therefore prepared a 3d cup as before; the quicksilver did not ascend 

 in the removal, but when immersed it fell very swiftly : that in the spare tube 

 sunk into the bulb, and that in the standard descended much quicker than be- 

 fore, till it came to 400°; after which it fell gently to 430°, and did not go be- 

 yond this point. As this was a greater degree of cold than that which professor 

 Braum said quicksilver would freeze at, he determined to break his spare tube, 

 which was easily done by a stroke with a pair of scissars; the quicksilver in a fall 

 of about 6 inches was flattened, and some globuli appeared at the bottom of a 

 tea-cup in which it was received. Mr. H. repeatedly struck the cake with a 

 hammer, and heard it give a deadish sound like lead, as M. Braum justly ex- 

 presses it. The quicksilver liquified in about 6 or 10 seconds. The surface, 

 when frozen, was finely polished. Mr. H. imagines the internal part of the 

 globe was not frozen, and that the force of the fall having flattened it, might 

 crack the external coat or shell of congealed quicksilver, and permit the globuli 

 which he saw to escape into the cup. On taking the standard thermometer out 

 of the mixture, it fell 10° lower than when the bulb was immersed; but it soon 

 began to ascend, and being taken into his room, it rose to 40 above O. 



Having succeeded thus far in his first attempt to freeze quicksilver, he was 

 anxious for another opportunity; but sometimes business, and want of a suffi- 

 cient degree of cold in the air at other times, obliged him to defer it till the 

 11th of February, which was very clear, and the thermometer stood at 36° be- 

 low O. Mr. H. began the operation at 45 minutes past 8: the instrument, being 

 at 28°, was put into a large tea-cup with the mixture as above, together with a 

 spare tube, graduated by himself; the quicksilver in the latter subsided into the 

 bulb, which was only 200° below ; in the standard thermometer it sunk to 

 447° at 59 minutes after 8 o'clock. Finding it did not go any lower, he removed 

 it into a 2d cup, prepared as before ; but the quicksilver showed no alteration in 

 it. After waiting a considerable time, he removed it into a 3d; but in the 

 removal, the quicksilver rose to 380° below O. Mr. H. imagined he had put in 

 too much spirit in proportion to the snow, and therefore added more of the 

 latter, by which means it subsided to 408°; and after standing at this point for 

 some time, it rose to 406°; and soon after, at 10 minutes after Q o'clock, it 

 rose with great celerity and full of bubbles, till it came to 160 above 0, and in a 



