591 



change of temperature is allowed for. The most important result 

 in the former case is the relation between pressure and velocity, 

 which is shown to be that which is expressed by the equation 



from which several new results are obtained. 



With respect to the velocity of sound, which has hitherto been 

 found experimentally to exceed the velocity obtained by theory, it is 

 shown that the value obtained by approximative methods is the 

 minimum limit of sound- velocity, so that the actual velocity will 

 always be greater ; the excess depending upon the intensity and 

 genesis of the sound. It is shown that all the parts of a wave do 

 not travel at the same rate, a circumstance which leads to the for- 

 mation of a bore in the front of the wave. Several previously unex- 

 plained phenomena, which have been recorded by different experi- 

 mentalists, such as double reports of fire-arms heard at a great 

 distance, the outrunning of one sound by another observed by 

 Capt. Parry, the comparative powers of different gases of trans- 

 mitting sounds, and the laws of transmission of sound from one 

 medium to another, are accounted for in this paper, and directly 

 deduced from the integral of the equation of wave-motion. 



IV. "Contributions towards the History of the Monamines." 

 By A. W. HOFMANN, LL.D., F.R.S. Received November 

 25, 1858. 



2. Action of Bisulphide of Carbon upon Amylamine. 



In a note on the alleged transformation of thialdine into leucine, 

 addressed to the Royal Society about eighteen months ago*, I 

 alluded to a crystalline substance observed by Wagner when sub- 

 mitting amylamine to the action of bisulphide of carbon. This sub- 

 stance was not analysed, but considering its mode of formation, 

 Wagner suggested that it might possibly be thialdine. 



Amylamine. Thialdine. 



* Proceedings, vol. viii,, Op. 4. 



