PROCEEDINGS OF THE POLYTECHNIC ASSOCIATION. 455 



American Institute Polytechnic Association, ) 



May ?>\st, 1866. \ 



Prof. Samuel D. Tillman in the chair; Mr. T. D. Stetson, Secretary. 



The following notes on science, from the pen of Prof. Joy, were 

 presented : 



A New Mineral. 

 Professor Wohler, Gottinhen, has discovered a new mineral in 

 some platinum ore of Borneo. It forms black, semi-metallic, very 

 brilliant grains, similar to crystalized iron. The specific gravity 

 varies from six to nine. It consists of a compound of sulphide of 

 osmium and sulphide of ruthenium. This is the first time that 

 the platinum metals have been found in combination with sulphur, 

 and will at once be seized upon by the advocates of the theory 

 that the sulphur in the auriferous pyrites of Colorado is in chem- 

 ical combination with the gold, as gold is classed by them in the 

 platinum group. Wohler proposes the name " Laurite," for the 

 new mineral, an account of which he will soon publish in the 

 German journals. 



Preparation of Pure Carbonic Acid. 



Carbonic acid is employed in so many industries that its pure 

 and economical preparation has engaged the attention of our in- 

 ventors and chemists. 



M. Ozouf, a manufacturer of artificial mineral waters, has pro- 

 posed the following method : The carbonic acid resulting from 

 the combustion of charcoal, or from any fire, is passed through a 

 cold solution of carbonate of soda — all of the impure gasses pass 

 off, while only the carbonic acid is absorbed and the simple car- 

 bonate becomes a bi-carbonate. The extra carbonic acid is after- 

 wards driven off by heat and employed as desired, in a perfectly 

 pure state. The carbonate of soda can be used repeatedly without 

 undergoing any deterioration. This process enables the manu- 

 facturer to employ any convenient material for the preparation of 

 carbonic acid in the first stage, as it is always pure in the second 

 stage of the operation. Usually in the manufacture of soda water, 

 the acid is obtained from marble dust, by the action of sulphuric 

 acid upon it, and may be contaminated by invisible impurities in 

 the marble. 



It has been proposed to subject the gases resulting from com- 

 bustion, to an immense pressure, by which only the carbonic acid 



