Royal Society. a’ Tot 
paper, which is the third and concluding one on this curious sub- 
ject, entered into a very wide field of physiological research, and 
embraced many siugular. conclusions and general inferences, 
which cannot be adequately detailed in this abstract. The author 
states, that the sanguiferous system can exist independent of the 
nerves; but the latter can stimulate the former, or retard and 
even totally obstruct it. He next tock an extensive view of se- 
cretion, as connected with these systems, the ganglia and spinal 
marrow. Animal heat he considers a secretion. When the fluids 
secreted by the giands are accumulated, secretion is not there- 
fore suspended ; on the contrary, its continuance is necessary to 
the healthy state of the glands and the other vital functions. 
Secretion and galvanism he thinks produce similar effects. - In 
conclusion the author observed, that m all his experiments he- 
had, wherever it was practicable without injury to the result, de- 
stroyed the sensibility of the animal previous to the commence 
ment of his operations, and had also avoided all unecessary Te- 
petition of cruel experiments, or ally useless waste of animal life. 
He proceeded to lay down some general and very judicious rules 
to avoid cruelty in making such experiments, and reflected on 
the conduct of some French physiologists in this respect. The 
object, he observed, of such operations is the ultimate advantage 
of society : if that be obtainable, it was weakness, and not ha- 
amanity, to reject or decline them; if not, it would be wanton 
cruelty. 
A letter from Dr. Brewster to the right lionourable President 
was read, relating some new experiments on the double refractive 
powers of fluate of lime and muriate of soda. Haity had justly 
observed, that all crystals have regular cubes, or tetrahedrons ; 
for their integral molecules are devoid of the property of double re- 
fracting crystals. Malus and Biot confirmed this observation ; but 
Dr. B. has discovered, that under peculiar cireurnstauces fluate of 
jime and muriate of soda have a double refractive power, and 
polarize light. He found that a mass of fluate of lime, having 
2 cube in the centre, but surrounded with different facets, pola- 
rized light ; but that the light passed through the cubie crystal 
without any change. Muriate of soda, some erystals of which 
rneasured three inches, gave very fine colours ; blue with comple- 
went of red, red with complement of yellow, &c. This discovery 
not only contributes to confirm the accuracy of crystallography, 
but will also facilitate its progress, as it must tempt many person’ 
to direct their attention to a branch of science so fertile, and so 
curious in its phenomena, ' 
Feb. 15. Two mathematical papers were laid before the So- 
ciety by professor Robertson, F.R.S. but they were of a nature 
not proper for general reading. 
, K Mr, 
