520 Mr. Fox on the Temperature of 



1st. Lampic acid reduces the salts and oxides of mercury 

 and silver with effervescence and evolution of carbonic acid 

 gas ; and it possesses this character in its own nature, and 

 independently of any matters not of an acid nature by which 

 it may be accompanied. 



2nd. It is obvious from this character, and from the ap- 

 pearance and properties of its salts, that lampic acid is prin- 

 cipally formic acid, but mixed with a small quantity of acetic 

 acid. 



In the memoir alluded to, M. Liebig further states, that by 

 the action of potash on alcohol a small quantity of an organic 

 acid is produced, the salts of which reduce with the aid of 

 heat the salts of mercury and silver, without effervescence. 

 I have here only to repeat what I had previously stated after 

 a detailed examination of this acid, that according to my ex- 

 periments it reduces the salts of mercury with effervescence ; 

 and that this character and the appearance and properties of 

 its salts show that it is entirely analogous to lampic acid in its 

 nature. In other words it is formic acid mixed with a little 

 acetic acid. 



In my examination of it, as in that of lampic acid, I was 

 formerly led to over estimate the proportion of acetic acid 

 contained in it, from supposing the salt deposited when it is 

 heated with peroxide of mercury to be acetate of mercury, 

 whereas I have now little doubt that it really is to a great ex- 

 tent formate of mercury. From this acid being produced only 

 in small quantity it is usually examined in a very dilute state, 

 and on this account the appearance of effervescence when heated 

 with the salts of mercury occasionally escapes observation. 

 It so happens that it was the previous examination of this 

 acid which led me to perceive the nature of lampic acid, as 

 afterwards experimentally ascertained. 

 Edinburgh, Sept. 22, 1837. 



LXXIII. Substance of a Communication on the Temperature 

 of some Mines in Cornwall a?id Devonshire, made by Robert 

 Were Fox, to the Royal Geological Society of Cornwall at 

 their last Annual Meeting.* 



T N the following table I have given the results of observa- 

 -* tions on the temperature of mines which I have reported 

 from time to time to the Cornwall Geological Society and 

 other societies ; and I have selected those experiments only 

 which were made at or near the deepest parts of the mines 



* Communicated by the Author : see our hist Number, p. 480. 



