150 Proceedings of Philosophical Societies. [Aug. 



vessel is made air-tight, and is made in the shape of a still and 

 receiver. As soon as the common still is made to boil, the steam 

 is conveyed into the receiver by means of pipes, and allowed to 

 pass till it has expelled the air ; then the stop cocks are shut, and 

 the steam passes through the worm as usual. It speedily heats the 

 water surro'i tiding the worm, which in consequence of the vacuum 

 distils over in considerable quantity. 



At the same meeting, part of a paper by Mr. Porrett was read ; 

 On the Salts commonly called triple Prussiates. Mr. Porrett began 

 bv stating clearly and concisely the striking differences between the 

 common prussiates, made by uniting prussic acid directly to the 

 bases, and the triple prussiates made by boiling the base upon 

 prussian blue. The triple prussiates contain in all cases the black 

 oxide of iron ; yet its presence cannot be detected by any reagent. 

 The reason is, as Mr. Porrett has ascertained, that the triple prus- 

 siates are not in reality triple salts, nor do they contain any prussic 

 acid. They consist of an acid hitherto unknown, combined with 

 the base, and neutralized by it. This acid he calls ferrvreted chya- 

 zic acid, ( a name composed of the first letters of the wo;ds carbon, 

 hydrogen, and azote, with the syllable ic added), because it is 

 composed of black oxide of iron, carbon, hydrogen, and azote. 

 When triple prussiare of soda is dissolved in water, and the solution 

 acted upon by the galvanic battery, the soda appears at the negative 

 extremity, while the oxide of iron and prussic acid are evolved at 

 the positive extremity, and, uniting, constitute Prussian blue. 

 Had not the iron constituted a part of the acid, had it been a base, 

 it would have been evolved at \he negative extremity of the bat- 

 tery. 



Mr. Porrett dissolved a quantity of triple prussiate of barytes in 

 water, and added to it a quantity of sulphuric acid exactly sufficient 

 to separate all the barytes. The consequence was, that the sulphate 

 of barytes, separating the acid of the triple prussiate, remained in 

 solution in water. It had a yellow colour, and no smell. When 

 slightly heated it was decomposed, the white prussiate of iron 

 falling down, which speedily became blue by absorbing oxygen. 



Other acids may be obtained by the combination of other sub- 

 stances besides oxide of iron with the compound base of prussic 

 acid. Thus sulphur combines with it, and forms what the author 

 calls sulphureted chyazic acid, which has the curious property of 

 precipitating peroxide of iron blood red. I regret that the re- 

 mainder of this curious paper was not read, so that it is not in my 

 power to continue the account of it any further. At the end of 

 the session of the Royal Society, there is always such an overflow 

 of papers, that it is not possible to read them all quite through in 

 one night. Hence they are generally curtailed. 



A paper was also read, written by Mr. Houghson, on the forma- 

 tion of bones. For the reason just assigned, I can give but an im- 

 perfect account of it. From his observations, made on foetuses, 

 the author concludes, that the first commencement of bone is an 



