Observations 07i external Perception, ^c. 193 



difficult and the others more easy to decompose, the compounds 

 of hydrogen corresponding with the first in the manner which I 

 have explained, are tlie only ones which can he obtained, at least 

 in the isolated state ; and that those Vv'hich correspond in the same 

 manner with the less stable combinations of oxygen are either 

 impossible, or cannot exist but when united to a third body. 

 According to this addition of four molecules or of an entire par- 

 ticle of hvdrogen to the number of the molecules of oxygen as- 

 sumed bv the different bodies in tlieir most stable combinations 

 with this last gas, we find six molecules of hydrogen when there 

 are two of oxvgen in these combinations, and eight when there 

 are four. 



The same considerations also lead us to foresee, according to the 

 representative forms of their particles, what are the gases which 

 water cannot absorb, but in very small quantity, by the simple 

 interposition of some of their particles between those of water, 

 and those which the same liquid is susceptible of absorbing in 

 large quantities, and forming with them true combinations. 

 [To be continued.] 



XXX^^ On Mr. Fearne's Ohtervations on external Per- 

 ception, &c. By T. FoRSTERi Esq. 



To Mr. Tllloch. 



Sir, In a paper On external Peix-eption, recently published in the 

 Pamphleteer, bv Mr. Fearne, he has maintained an opinion that 

 our perception of external objects is not by means of the five 

 senses alone, but that it is an act of the mind. As this doctrine, 

 at least as exj)ressed in the manner he has delivered it, is some- 

 what novel ; and as it coincides with an opinion which has re- 

 sulted from the last discoveries into the phvsiology and structure 

 of the organs of the brain, I am induced to point out to the me- ^ 

 taphysical speculator the great similarity of opinions drawn from 

 different sources, on a subject which has so frequently engaged 

 the attention of philosophers. I do not proceed with Mr. 

 Fearne in all his reasonings throughout the course of his various 

 metaphysical inquiries, but allude specially to the opinion that 

 the sensation of objects by means of the five external senses is 

 not sufficient to produce the belief of the external existence 

 of bodies. But I believe tlie perception of the external 

 bodies to be the consequence of an organic apparatus quite 

 as material as the nerves of the five senses. In short, the organ 

 of individuality, or that part of the front lobes of the brain 

 above the nose, in the middle and inferior part of the forehead, is 

 Vol. 45. No. 203. March. 181.3. N the 



