Neiv Observations on Volcanoes and their Lava. 219 

 /5ther division of the flues be made in the manner shown 

 fig. 2, it might form a steam-pipe or flue, running the course 

 of the air and fire-flues to convey steam to one or more 

 apartments of the stove, or extended beyond the stove for 

 heating the room in which it stands. One of the air-flues 

 might occasionally be adapted to this use. It is obvious 

 that the power of steam in a heated apartment would be not 

 only greater, but better kept up. In steaming it would be 

 necessary to close the apartments of the stove, and to give 

 air to the fuel by a different course. 



As the stove is not confined in its dimensions, so neither 

 is it necessarHy of the form described in the drawing, nor 

 are the apartments necessarily three : all these particulars 

 admit of variation according to local or other circumstances. 

 It is evident that the air-flues themselves may be converted 

 into chambers for drying, &c.; and the fire-place of fig. 3. 

 is well adapted to receive an apparatus for the decomposi- 

 tion of coal, &c.; for producing all the effects of the thermo- 

 lamp, or illuminated smoke, &c. But it is needless to enu- 

 merate the many ceconomical and philosopliical uses to 

 which the stove may be applied. It is sufficient for the 

 present purpose if I have rendered the principle and plan 

 intelligible, the artist and manufacturer will then be at no- 

 loss in adapting it to the particular object which he may re- 

 quire it to accomplish. 



XXXVII. New Observations on Volcanoes and their Lava. 

 By G. A. De Luc. 



[Concluded from vol. xxii. p. 271.] 



jyi. Humboldt, considering basaltes as of aqueous forma- 

 tion, attributes the same origin to obsidian and to what he 

 calls basaltic porphyries. If all the volcanic products, which 

 at the first glance do not seem to have been treated by fire, 

 ouo-ht to be considered as natural rocks, there are vcrv Ic^.^' 

 antient lavas which could l)e rccairniscd as a product of lire. 

 It is thus that count de Hordi, \\\w had ncvcithcless visited 

 Muiif has kU'J that iij. fuudamtnUl stone is A granils mixed 



wiih 



