Production of Boracic Acid and Ammonia. 251 



having their heads removed, were filled with broom-plants and 

 twigs, and were placed over parts of the area from which the 

 boracic acid had been carefully cleared away. In a few days 

 the acid had been vaporized into them, and had deposited in 

 crystals like hoar-frost all over the twigs. On digging down 

 for about eight inches, wherever this boracic acid occurs on 

 the surface, a red-hot mass of sal-ammoniac is always found ; 

 sulphur comes up also with these. 



" This volcano is said to realize to the proprietors about 

 £1000 per annnm. The products are sulphur, from fusing 

 the stone ; sal-ammoniac, from the lixiviation of the scoria or 

 lava ; and boracic acid, large quantities of which are reported 

 to be obtained annually from this source. The sides of the 

 volcano are of sulphur-stone, and brimstone is dug up all 

 around for miles. The mountains produce also alum, which 

 exists in the schistose rocks ; and there are likewise large beds 

 of lignite ; but nowhere do we find sal-ammoniac or boracic 

 acid, either at Vulcano or in Tuscany, separate from one 

 another. Had they done so, we should certainly have found 

 traces of it somewhere, but, so far as I know, this has never 

 been observed ; and it is certain that, at Vulcano, whenever 

 the acid lying on the surface is removed, the melted matter 

 underneath is found to contain salts of ammonia. It follows, 

 therefore, that they must both be produced from one and the 

 same stratum, in which they occur in some form of combina- 

 tion, from which they are separated by heat. In what sub- 

 stance can they exist together?" 



These observations of my/riend were accompanied by speci- 

 mens of the sublimate scraped from the surface of the crater, 

 and of sal-ammoniac, which have enabled me to do something 

 towards the solution of the question with which he terminates 

 his letter. The ammoniacal salt was not a portion of the 

 fused mass mentioned above, but had been obtained by its lixi- 

 viation and subsequent crystallization. I did not, therefore, 

 attempt to make any experiments with it. The boracic acid, 

 however, was in the state in which it was found, and had the 

 form of white glistening scales of a nacreous lustre, tinged 

 in parts with traces of adherent sulphur, and possessing a greasy 

 talcose feel. It was, in the first instance, boiled with diluted 



