14 Dr. Schafhaeutl oji Sleam considered as a 



which will be quite sufficient to show the correctness of my 

 statement. 



Required the result of dextans. siliqua. ceraces. 

 The reduction of dextans : 



_ igin. sipos _ andras. quinas _ quinas 

 "~ andras. calcis ~ andras. caicis calcis 

 = semiuncia. quicunx. 

 The very first step of which uses the decimal scale. 



IV. Om Steam considered as a Conductor of Electricity. By 

 Dr. Charles Schafhaeutl*. 



IN the last Number of the Philosophical Magazine, the 

 electricity obtained from a jet of high-pressure steam was 

 considered to be of similar origin with that obtained from the 

 insulated and separated positive metallic disc of Volta's Elec- 

 trophorus. 



On this point, the first question which presents itself is, in 

 what relation does steam or water-gas stand with the conduct- 

 ors or non-conductors of electricity. 



It is well known that moist air is a conductor of electri- 

 city, and dry air, viz. air which contains less water-gas than 

 it is capable of containing according to its temperature, is a 

 non-conductor of electricity; but, besides this, I am not aware 

 of any experiment made to ascertain the conducting power of 

 pure steam without being in contact with water or mercury, 

 and I therefore determined to ascertain this question by ex- 

 periment. 



The ends of a glass tube, about two inches long and a 

 quarter inch interior diameter, were drawn out over a lamp 

 to points, and bent upwards in a right angle. A thick pla- 

 tinum wire, with a small ring formed at each end, was then 

 inserted into one end of the tube, and the glass melted around 

 it air-tight. Water was then poured into the tube and boiled 

 till only about two drops remained, when another platinum 

 wire was inserted at the other end, and the hole quickly her- 

 metically closed as before. The distance between the ends of 

 the two wires in the tube was about one inch and a quarter, 

 and the tube in this state contained of course nothing but 

 water-gas and some liquid water. 



This tube was now inserted close to the bulb of a thermo- 

 meter into a small sand-bath f, and covered with the sand, 

 excepting the two vertical ends. 



• Communicated by the Author, whose former communication on the 

 subject appeared in our last Number; L. E. and D. Phil. Mag. vol. xvii. 

 p. 449. 



•f- I cannot omit to mention the kindness I experienced from the gentle- 

 men lecturing at the Adelaide Gallery, in allowing me the use of their 



