272 Dr. Hare's Electrical Machine, S^c. 



As compounds, consisting of a basacigen body, hydrogen and a 

 radical, do not, when presented to bases, enter into combination ; but 

 are on the contrary, decomposed so as to allow another radical to 

 take place of their hydrogen, it is inconsistent with chemical law, as 

 stated by Berzelius,* or my definition of acidity, (page 9,) to desig- 

 nate them as acids. 



I have called the electro-negative " ■protocyanure'^ of iron of Ber- 

 zelius, cyanoferroMS acid, because there is " sesquicyanure" in the 

 " cyanureferrico-potassique^^ of that author, which by analogy with the 

 nomenclature of the oxacids, is entitled to the appellation of cyano- 

 ferric acid. 



Art. V. — Description of an Electrical Machine, with a Plate four 

 feet in diameter, so constructed as to he above the Operator: 

 also of a Battery Discharger employed therewith: and some Ob- 

 servations on the Causes of the Diversity in the Length of the 

 Sparks erroneously distinguished by the terms Positive and Neg- 

 ative ; by R. Hare, M. D., &;c. Stc. &ic. 



The opposite engraving represents a machine with a plate four 

 feet in diameter, which I have recently constructed so as to be per- 

 manently affixed to the canopy over the table of my lecture room. 



This situation 1 have found convenient even beyond my expecta- 

 tions, as the machine is always at hand, yet never in the way. In 

 lecturing, with the aid of a machine on the same level with the lec- 

 turer, one of two inconveniences is inevitable. Either the machine 

 will occasionally be between him and a portion of the audience, or 

 he must be between a portion of the audience and the machine. 

 Situated like that which I am about to describe, a machine can nei- 

 ther hide the lecturer, nor be hidden by him. With all its power 

 at his command, while kept in motion by an assistant, he has no 

 part of it to reach or to handle besides the knob and sliding rod of 

 the conductor, which are in the most convenient situation. 



The object of this machine being to obtain a copious supply of 

 electricity for experiments, in which such a supply is requisite, it 

 was not deemed necessary to insulate the cushions and the axis, as 

 in the electrical plate machine which I employ for experiments re- 

 quiring insulation .f 



* Traite, page 41, vol. ii. 



t See this Journal for 1828, vol. vii, p. 108 ; or London Phil. Mag. for 1823, vol. 

 xxiii, p. 8. 



