H2 Intelligence and Miscellaneous Articles, 



nected with an apparatus, evolving dry chlorine gas : the apparatus 

 is first filled with this gas, the sulphuret of iridium is heated in the 

 bulb by a double-wicked spirit lamp. By the gradual action of the 

 heat, sulphur and its chloride are volatilized ; the mass which has 

 hitherto been black, crystalline and brilliant, becomes brown and 

 afterwards yellowish red. When no more chloride of sulphur ap- 

 pears, the heat is to be raised so as to render the bulb strongly red 

 hot, chlorine is again to be passed in until no further change 

 appears. 



The experiment is then finished ; the lamp is to be removed, and 

 the apparatus is to be allowed to cool, full of chlorine. The chlo- 

 ride of iridium then forms an orange-coloured mass, which imme- 

 diately dissolves, without residue, in cold distilled water ; the solution 

 is transparent and of a deep orange-red colour. This is the chloride 

 of iridium, it has sometimes a purplish tint, and it then possibly 

 contains some sesquichloride. If any residue remain it is either 

 metallic iridium or sand, or white brilliant spangles of osmo-iridium, 

 which has escaped all the previous reactions ; they may easily be 

 separated by washing. 



If the iridium contains osmium the same process is employed, but 

 the chlorine is used moist ; when the chloride of sulphur has dis- 

 tilled, white thick vapours appear, which when sublimed into a 

 cool tube, give a crystalline mass of fine white osmic acid, while all 

 the iridium remains in the bulb. If the chlorine were dry, chloride 

 of osmium would sublime, which condenses with greater difficulty 

 than oxide of osmium, and is easily carried away by excess of chlo- 

 rine. But by the aid of moist chlorine, the osmic acid is obtained 

 isolated, and it may be conveniently collected in a long and large 

 tube, drawn out and kept cool at the end, while all the chloride of 

 iridium remains iu the bulb ; by this process the two metals may 

 be separated. 



M. Fellenberg learnt by chance that moist chlorine favours the 

 separation of osmium and iridium ; he observed, that in a parallel 

 experiment as soon as the tube which contained the chloride of cal- 

 cium for drying the gas, was moist, and that all the chloride of sul- 

 phur had distilled, white vapours of oxide of osmium were formed, 

 which were received in a long cold glass tube ; these were recog- 

 nized by their crystalline form, their action upon sulphurous acid, 

 and on tinctura of galls. 



With perfectly dry chlorine, no trace of oxide of osmium is ob- 

 tained, but only chloride which condenses in the state of a reddish 

 brown crystalline powder, the greater part of which is carried off 

 and may be collected in a bottle containing distilled water. — Jour- 

 nal de Fharrnacie, November 1837. 



ON LACTIC ACID IN SOUR-CROUT. BY M. LIEBIG. 



Sour-crout contains an acid which is not volatile and which is 

 not destructible by digestion, for it continues to act in a peculiar 

 manner on the intestines. It appeared probable that it was lactic 

 acid J it is formed, in fact, by a peculiar fermentation, to which the 

 name of the viscous fermentation has been properly applied. 



