t 

 1814.] Linncean Society. 46.1 



off every time the metal was lieated to redness; so that the process 

 would never advance: but if the vegetable juice or cow-dung 

 employed supplied sulphur, or any analogous principle, we can see 

 how the repeated heatings would facilitate the combination, and 

 how fusion would retard it. 



Dr. Heyne's observations on the milk of plants were curious and 

 valuable, but of too miscellaneous a nature to admit of abridgment 

 liere. 



On Thursday, the 1 9th of May, a paper by Dr. Brewster was 

 read on the optical properties of hot glass. The author discovered 

 that glass, when heated nearly to redness, polarizes and depolarises 

 light, and forms two images, one of which coincides with the 

 other. Hence it is analogous to doubly refracting crystals. Tiie 

 beautiful coloured rings produced by topaz were not perceptible in 

 this case ; but it occurred to Dr. Brewster that glass, in order to 

 produce them, must be in a state of fusion. As it was not possible 

 to examine its optical properties in that state, Dr. Brewster had 

 recourse to the glass tears formed by dropping melted glass into 

 cold water, on the supposition that from the sudden cooling of the 

 outer coat the interior part of these tears would be in the same state 

 as melted glass, or at least their idtimate particles at the same dis- 

 tance from one another as in melted glass. He found accordingly 

 that these tears produced the coloured rings in question. He found 

 that this tear has regular axes of crystallization, the axis of the 

 conical tail, and a line perpendicular to it, corresponding with the 

 short and the long diagonals of a rhomboid of calcareous spar. 



At the same meeting a paper by Ca|)tain Kater was also read, 

 containing farther experiments on the light of the Gregorian and 

 Cassegraiaian telescopes. He examined the quantity of light passing 

 through a glass lense before and behind the focus. He found the 

 light behind the focus to that before as 1000 to about 650, or some- 

 what less in the greater number of experiments. These results 

 approach to the degree of light observed in the Cassegrainian and 

 Gregorian telescopes, and therefore serve to confirm Captain 

 Kater's preceding observations. 



At the same meeting a paper by Mr. Hcrschell was announced, 

 on some remarkable properties of mathemaiical analysis. As thi* 

 paper was not read, it is impossible to give any account of it. 



LINN -9=: AN SOCIETV. 



On Tuesday, the 3d of May, the remainder of Dr. Leach's 

 paper, exhibiting a tabular view of four classes of anio)aK. consi- 

 dered by LmnfcKus as constiliiting but one class, was read. 



On Tuesday, tlve u'tth of May, the following ollicc bearers wer« 

 chosen for the ensuing year : — 



Prksiwf.nt— James Edward Smith, M.D. F.K.S. 

 SECHiiTAHiKS--AU'xaiuler Macleav, Esti. F.it.S. 

 Mr. Kichard Tavlor. 



