&&'<& p 



' V 



v<* . 



Mr. Connell oh ///<? Natu^e\)J \LninpicAcid. 353 



in order that by adopting these hours the'true hours of mean 

 temperature and the critical interval may be determined. In 

 order to do this, we must, if we do not know it, deduce the 

 mean temperature of the place of observation from the pre- 

 ceding or other tables, that is by correcting the temperatures 

 in the register by the differences between the temperature in 

 the table at the same hour and the mean temperature of the 

 day. The mean of the two mean temperatures thus obtained 

 may be considered as the mean temperature of the place. 

 Then from the rales of ascent and descent at the times of the 

 morning and evening mean, as given in the preceding tables, 

 or otherwise ascertained, and the differences between the two 

 registered temperatures and the mean temperature as already 

 obtained, we may find the quantities to be added or subtracted 

 from the interval between the two observations in order to ob- 

 tain the critical interval. 



LIII. Observations on the Nature of Lampic Acid. 

 By Arthur Connell, Esq.* 



\ FEW years ago I showed that this acid liquid, as pre- 

 ** pared in the usual way by exposing the vapour of aether 

 to the action of a coil of glowing platinum wire, contains a 

 large quantity of formic acidf. The latest researches with 

 which I am acquainted on lampic acid are those of Stass, 

 Martens and Marchand, who, whilst they admit the presence 

 of formic and acetic acid in it, maintain that it also contains 

 a third acid, viz. the aldehydic. Although these researches 

 were made some years ago, and I had seen short notices of 

 them, it was not until lately that I had access to Erdman and 

 Marchand's Journal of Practical Chemistry, which contains 

 a full account of them J; and I now offer a few observations 

 upon them, with reference to the alleged existence of alde- 

 hydic acid in lampic acid. 



I may observe in commencing, that even were it established 

 that lampic acid contains a third acid besides the formic and 

 acetic, it by no means follows that that third acid is to be 

 viewed, as has been done by some chemists, as the peculiar 

 and characteristic acid of the lampic mixture, and as confirm- 

 ing Liebig's original view, that lampic acid may be regarded 

 as aldehydic acid. The very fact that the proportions of these 



* Read to the Chemical Section of the British Association, &c. held at 

 Southampton, and communicated by the Author. 



f Lond. and Edinb. Phil. Mag. vol. xi. p. 175. 



X Vols, xviii. and xix. 

 Phil. Mas. S. 3. Vol. 29. No. 195. Nov. 1846. 2 B 



