1818.] On the Sounds produced by Flame in Tubes. 21 



I have not examined the action of ammonia upon the other 

 chlorides ; with some of them it would probably form neutral 

 compounds, with other combinations similar to those described. 

 Nearly all those mentioned are formed by the exertion of an 

 affinity so weak that it is overcome by the attraction of water 

 for the ammonia, and yet in one instance it is capable of giving 

 a definite crystalline form. 



The facility with which many of them afford dry ammoniacal 

 gas at low temperatures in considerable quantities, may per- 

 haps in some cases make them convenient sources of that sub- 

 stance*; 19 grains of the compound with chloride of lime 

 which had been made many days, gave 19*4- cubical inches of 

 gas. They also offer a convenient means of ascertaining the 

 specific gravity of ammonia, by the quantity of gas given off, 

 and the loss of weight in the substance. 



On the Sounds produced by Flame in Tubes, $c. f 



THERE is an experiment usually made in illustration of the 

 properties of hydrogen gas, which was first described by Dr. 

 Higgins in the year 1777J, and in which tones are produced 

 by burning a jet of hydrogen within a glass jar or tube. These 

 tones vary with the diameter, the thickness, the length, and 

 the substance of the tube or jar ; and also with changes in the 

 jet. They have frequently attracted attention, and some at- 

 tempts to explain their origin have been made. 



After Dr. Higgins, Brugnatelli in Italy, and M. Pictet at 

 Geneva, described the experiment, and the effects produced 

 by varying the position and other circumstances of the jet and 

 tube ; and M. De la Rive read a paper at Geneva (published 

 in the * Journal de Physique,' Iv. 165), in which he accounted 

 for the phenomenon by the alternate expansion and contrac- 

 tion of aqueous vapour. That they are not owing to aqueous 

 vapour, will be evident from some experiments to be described. 

 I have no doubt they are caused by vibrations, similar to those 

 described by M. De la Rive ; but the vibrations are produced 



* See ' Condensation of Gases.' 



t Quarterly Journal of Science, v. 274. 



Nicholson's Journal, vol. i. p. 130. 



