

TRANSACTIONS OF THE SECTIONS. 39 
prism, with the direct terminal face. The other exhibited the faces of the second 
six-sided prism, of a twelve-sided prism, and of a twelve-sided irregular pyramid. The 
last of those forms is here observed for the first time. 

On the Relative Electro-Negative Powers of Iodine and Fluorine. 
By the Rev. T. Knox. 
The object of this paper was to controvert the statement made by Brande in his 
‘ Chemistry,’ that the fluorides are not decomposed by chlorine or iodine; and to 
show, as the result of experiments, that fluorine has been erroneously placed above 
iodine as a negative element. 
On the Electricity of High-Pressure Steam, and a description of a Hydro- 
lectric Machine. By W. ARMSTRONG. 
This paper recapitulated the circumstances which first drew the attention of the 
author to steam as a source of electrical power, and the successive steps by which 
he had succeeded in arranging apparatus to render it effectual. The powers of the 
* Hydro-electric Machine’ were described and illustrated by a diagram. The author 
assents to Dr. Faraday’s opinion, that the force with which the particles of water are 
rubbed against the glass, is in this case the cause of the development of electricity. 
On the late Fires at Liverpool, and on Spontaneous Combustion. 
By A. Booru. 
This communication consisted of an enumeration cf cases in which fires had, as it 
was supposed, originated in the spontaneous combustion of material used in manu- 
factures ; and the author suggested the propriety of instituting an extensive series of 
experimental inquiries into this class of pheenomena, which are but ill understood. 

On the Chemical Composition of Smoke, its Production and Influence on 
Organic Substances. By A. Boorn, F.L.S. 
——- 

On the Production and Prevention of Smoke. By Henry Dircxs. 
Mr. Dircks, referring in particular to the plans of Mr. C. Wye Williams for the pre- 
vention of smoke, thought it important to distinguish between open fires, and close 
fires or furnaces. Open fires would always allow an escape of absolute coal-gas, and 
admit atmospheric air to the chimney ; whereas the contrary would be the result with 
_ the close fires of engine-boiler furnaces. He said that the leading fact of consequence, 
in reference to the smoke, was, that it differed materially from the impure gas evolved 
from the coal in the furnace. The plans hitherto adopted by manufacturers were 
chiefly intended to burn smoke, and the prevailing principle of all such plans was to 
burn the largest quantity of fuel with the least quantity of air, The error of this 
method must appear to every one conyersant with chemistry. Smoke may be con- 
sidered as mere carbonaceous matter floating in an atmosphere of the ordinary in- 
combustible products of combustion; the admission of air to this smoke is of no value, 
as it will only cool it, and make it more readily deposit its sooty particles. The im- 
pure gas of the coal, on the contrary, may be inflamed bya due admixture of air. In 
conclusion, Mr, Dircks begged to state as a general principle, that on the large scale 
of the furnace, air, in as divided a form as possible to favour rapid diffusion mechani- 
cally, should be supplied to the impure gaseous products of the fuel independent of 
the supply of air to the solid fuel on the grate. Mr. Dircks said that the prin- 
gre he advocated was that practically carried out in the Argand furnaces of Mr. C. 
Wye Williams, 

Eulogium on the late Richard Kirwan, LL.D. By Dr. Pickexts. 
_ The author traces the progress of this very distinguished philosopher from the pe- 
riod when, by the death of his brother, who was accidentally shot while entering the 
