848 On Pyrophorus, and the making of Potassium. [Mat, 



brain extracted from Cuvier (loc. cit.), and show that there is 

 really no proportion beiweeu the degree of voluntary motion and 

 the size of tliis organ. 



Man and the ox 1 — 9 



Dog 1-8 



Horse and wild boar i — 7 



Hare and cat 1 — 6 



Sheep 1 — 5 



Mole 1—4-^ 



Rat 1— ;^x 



Beaver 1 — 3 



House mouse {rmis musculus) 1 — 2 



Mr. A. Walker has further observed, that " Dr. Spiuzheim has 

 most certainly erred in denominating the cerebellum the organ of 

 amativeness." I have not time to give the facts which have led 

 Drs. Gall and Spurzheim to hold this opinion, and must therefore 

 refer to Dr. Spurrheim's work on the Anatomy and Physiology of 

 the Brain, where the statements are fully detailed. 



I am, dear Sir, 



Your obedient servant, 



Wm. Elfdrd Leach. 



Article VII. 



On Pyrophonis, and the making of Potassium. By Dr. Hamel. 



In the appendix to vol. iv of Priestley's Experiments and Ob- 

 servations relative to various Branches of Natural Philosophy, 

 p. 481, mention is made of the following experiment of Mr. Wm. 

 Bewlv : — " I mixed equal parts of sal-tariar and vegetable or 

 animal coal, or sometimes three parts of the former with two of the 

 latter, and calcined them in the usual manner (for making Hom- 

 berg's pyrophorus). This composition, on being exposed to the air, 

 generally kindled in the space of half a minute or a minute. It 

 did not burn with so much vivacity as the vitriolic pyrophori, as it 

 contained no sulphur. I shall hereafter denominate this the alkaline 

 pyrophorus. It differs in no one circumstance from M. du Suvigny's 

 ventral pyrophori, except in its not containing that very principle to 

 which he ascribes their accension. Lest it might be suspected that 

 the salt of tartar which I employed might accidentally contain 

 vitriolic tartar, or vitriolic acid, 1 repeated the experiments with 

 tartar calcined by myself, as well as with nitre 6xed or alkalized by 

 deflagration with charcoal and with iron filings ; but in all these 



