1819.] extracted from Pyrites at Fahlun. 101 



least at first, are hydroseleniurets, which, by the influence of 

 atmospherical air, are converted in a short time into seleniurets 

 of the oxide, as I shall prove below. 



Seleniuretted hydrogen gas is easily decomposed by the action 

 of water and air. If the gas comes in contact with a moist 

 body, humidity absorbs it, the oxygen of the air decomposes it, 

 and the humid body assumes a cinnabar red colour. The sele- 

 nium thus deposited penetrates porous bodies, especially organic 

 bodies, so as not to be separated from them mechanically. A 

 piece of moist paper becomes red in the interior ; a piece of wood 

 is penetrated to some distance below the surface ; and a tube of 

 gum elastic, which had been employed in an experiment to 

 conduct the seleniuretted hydrogen gas, had its interior coloured 

 entirely of a fine red. 



This gas produces effects on the trachea and on the organs of 

 respiration, which may probably become dangerous. On the 

 interior of the nose, its effect is to produce at first an odour 

 exactly resembling that of sulphuretted hydrogen gas ; but 

 immediately after a sharp, astringent, painful sensation is per- 

 ceived on all those parts which the gas has touched. This 

 sensation is veiy analogous with that which is caused by silico- 

 fluoric gas ; but this last gas produces but little effect when 

 compared to that of seleniuretted hydrogen. The eyes become 

 immediately red and inflamed, and the sense of smelling is quite 

 lost. 



In the first experiment which I made on the odour of this 

 gas, I conceive that I let up into my nostrils a bubble of gas 

 about the size of a small pea. It deprived me so completely of 

 the sense of smell that 1 could apply a bottle of concentrated 

 ammonia to the nose without perceiving any odour. After five 

 or six hours I began to recover the sense of smell ; but a strong 

 rheum continued for about 15 days. 



On another occasion, while preparing this gas, I perceived a 

 slight hepatic odour, because the vessel was not quite close ; but 

 the aperture was very small ; and when I covered it with a drop 

 of water, small bubbles were seen to issue about the size of the 

 head of a pin. I put the apparatus under the chimney of the 

 laboratory, not to be incommoded with the gas. I felt at first a 

 sharp sensation in the nose, the eyes became red, and symptoms 

 of rheum began to appear ; but only to an insignificant extent. 

 In half an hour, I was seized with a dry, painful cough, which 

 continued for a long time, and which was at last accompanied 

 by an expectoration, whose taste was entirely analogous to that 

 of the vapours of a boiling solution of corrosive sublimate. 

 These symptoms were removed by the application of a blister to 

 the breast. The quantity of seleniuretted hydrogen gas, which 

 on each of these occasions acted on the organs of respiration, 

 was much smaller than would have been required of any other 

 inorganic substance whatever to produce sensible effects. It i 1 * 



