Chemical Science. 341 



the wall, in the direction of a line from this spot to the tree, I 

 cannot doubt that it passed the whole way from tlie tree under 

 ground. — Described bj/ Professor Kelloy. Silliman's Jour. ix. 84, 



7. Cold produced by the combination of Metals. — Some striking" 

 examples of depression of temperature during the liquefaction of 

 metals has been pointed out by Dobereiner. According to him 

 fusible metal is a compound of one atom of lead 103, one atom 

 of tin 59, and two atoms of bismuth 142; or it consists of an 

 atom of the combination of bismuth and lead, and an atom of the 

 combination of bismuth and tin. It becomes fluid at a tempera- 

 ture of 210°. The melting points of these alloys of bismuth 

 and lead, and of bismuth and tin, in a separate state, are respec- 

 tively between 325° and 335°, and between 268° and 280°. 



If 118 grains of -tin filings, 207 grains of lead filings, and 284 

 grains of pulverised bismuth, (the constituents of fusible metal,) 

 be incorporated in a dish of calendered paper with 1616 grains 

 of mercury, the temperature instantly sinks from 65° to 14°. He 

 even thinks it would fall so low as the freezing point of mercury, 

 could it be performed in temperatures somewhat under 32°. 



In like manner when 816 grains of the amalgam of lead, (4o4 

 mercur)^ +412 lead,) were mixed in a temperature of 68° with 

 6SS grains of the amalgam of bismuth, (404 mercury + 284 bis- 

 muth,) the temperature suddenly fell to 30°., and by the addition 

 of 808 grains of mercury, (also at 68°,) it became as low as 17°, 

 the total depression amounting to 51°. — Aim. Phil. N. S. ix. 389. 



8. Light produced during Crystallization. — Dobereiner states, 

 that a splendid instance of light produced during crystallization 

 was observed by M. Buchner, of Magonza, during the sublimation 

 of benzoic acid, previously mixed with pulverized carbon. The 

 sublimation was carried on in a tall glass cylinder upon a stove, and 

 when it had well began there appeared an uninterrupted succes- 

 sion of sparks, continuing for half an hour, and which ceased only 

 when the cylinder was removed from the stove. 



Dobereiner states, that he has reason to believe those salts, 

 containing no water of crystallization, are especially powerful in 

 producing light during their crystallization. — Gior. di Fisica^ 

 vii. 470. 



» 9. Colour of Glass as qfected by Light. — An effect is noticed at 

 p. 164, vol. xvi, of this Journal, due to the action of light upon 

 glass, containing oxide of manganese, it being found that glass 

 of a pale colour, or even colourless at first, by long exposure to 

 solar rays, became pink, whilst portions of the same glass, re- 

 tained in dark situations, were apparently unaltered. It occurred 



