116 Transmission of Electricity through Tubes of Water. [Aug. 



remained undissolved, and consisted chiefly of sulphate of 

 barytes. Traces of iron and manganese were also obtained, as 

 previously indicated by the blowpipe, but I could not detect any 

 appearance of magnesia. The mineral effervesces of course 

 very strongly with acids, and, when finely pulverised, its powder 

 has a very light flesh-coloured or rosy tint. 



According to Brande's Table of Prime Equivalents, the 

 weight of the atom of carbonate of barytes is to that of carbonate 

 of lime as 100 : 50, or as 2 : 1. The theoretical composition of 

 this mineral, therefore, (disregarding the insoluble sulphate, and 

 the metallic oxides, as not essential to it) accords very nearly 

 with that obtained by experiment, as appears below : 



Theoretical. Experimental. 



Carbonate of barytes 66*66 65-90 



Carbonate uf lime 33-33 33*60 



99-99 99-50 



Hence we may consider it as containing an atom of each 

 element. 



Article IX. 



On the Transmission of Electricity through Tubes of Water, fyc. 



By Mr. Lewthwaite. 



(To the Editors of the Annals of Philosophy.) 



GENTLEMEN, Rotherhithe, July 9, 1824. 



Allow me to intrude myself on your pages to correct an 

 error committed by Mr. Woodward in the last number of the 

 Annals. 



Mr. W. says, the effects of electricity on loose gunpowder 

 when transmitted through tubes of water, were communicated 

 by me to Mr. L. some time previous to the publication of his 

 letter. 



The natural inference to be drawn from this sentence is, that 

 I am indebted to him for the experiment in question. This, I 

 can assure Mr. W. is not the case ; it was originally communi- 

 cated to me by Mr. Tuther about fourteen years ago. The 

 experiment relative to the conducting power of ether, alcohol, 

 and acids, published in the Institution Journal, originated while 

 I was experimenting with the water tube, nor had I the least 

 idea that Mr. W. was investigating the conducting power of 

 those fluids until some time after the publication of my letter. 

 I am, Gentlemen, your humble servant, 



John Lewthwaite. 



P. S. An account of the experiment of firing loose gunpowder 

 by the water tube may be found in Imison's Elements of Science 

 and Arts, vol. i. p. 469. 



