Royal Sociely. 153 
heart, and arrested the pulsations. One drop of thre empy- 
reumatic oil of tobacco let fall on the tongue of a cat killed 
her, but did not destroy the pulsation so instantaneously. 
Mr. Brodie made a great number of experiments with the 
vegetable poison used by the American Indians to poison 
their arrows, and with nearly similar results. 
On Thursday, the 21st of February, a paper was read by 
H. Davy, Esq. LL.D. Sec. R.S. on a gaseous combination, 
of oxymuriatic gas and oxygen. 
Mr. Davy procured this extraordinary body by acting on 
hyperoxymuriate of potash by diluted muriatic acid. Mr. 
Davy stated, that it explodes by the application of a heat 
equal to that of the human body; and that though the 
oxygen and oxymuriatic gas expand in separating trom each 
other, yet heat and light are produced. The metals which: 
burn readily in oxymuriatic gas do not act upon this: body 
till itis decomposed. He described a number of properties of 
this compound, all of which he considered as strengthening 
his opinion of the undecompounded nature of oxymuriatic 
gas; and as particularly opposed to the idea of its contain- 
ing oxygen. Mr. Davy proposed the name zuthine or zu- 
thic gas for this hody trom its colour, which is bright yel- 
low; but he stated that he should be content to adopt any 
other name which might be considered as more appropriate. 
ROYAL SOCIETY OF EDINBURGH. 
On the 7th of January, Sir George Mackenzie continued 
his account of the mineralogy of Iceland, and described 
some very curious geological tacts. On the 21st he con- 
cluded bis mineralogical detail, with an interesting descrip- 
tion of Mount Hecla, and other volcanic districts. In this 
paper Sir George made some remarks which tended to place 
' obsidian and pumice in a conspicuous point of view, as 
relating to the different theories of the earth, and clearly 
proved their origin to be igneous; a position which has 
hitherto been denied by Werner and his pupils. 
On the 4th of February, Dr. Brewster read an ingenious 
paper on the longitude of the comet of 1770. _ Sir George 
Mackenzie described some remarkable hot springs in Ice- 
land. To one of these he gave the name of the alternating 
Geyser, as it spouted from two distinct orifices evidently 
connected within, but only from one at a time, whose 
operations alternated with those of the other, at, regular 
intervals of time. 
On the 18th, Professor Playfair read part of a biographical 
sketch of the late John Robison, LL. D. and Protessor of ° 
Natural 
