456 Capt. W. A. Ross on Pijrology, or Fire Analysis. [June 20, 



that the ingenious blowpipe of Bunsen, by which the breath is forced into 

 a jet of ignited gas itself, is utterly useless for the purposes, and to produce 

 the results detailed in these pages. The pyrocone thus formed is indeed 

 the counterpart of that produced by blowing into the pyrocone of a spirit- 

 lamp, except that its temperature is perhaps higher, with the deleterious 

 results mentioned in paragraph 12. 



The Fluxes. 



30. These are invariably supported on platinum-wire in the admirable and 

 perfect manner invented by Gahn, and, as soon as a pyrocone is applied, 

 assume the form of a spheroidal bead, which revolves or spins round upon 

 its centre with a rapidity proportional to the fluidity of the matter of which 

 it is composed. The " glasses " or " beads " thus formed, with the oxides 

 dissolved in them, may be quantitatively determined, as to their weight and 

 size, by means to be presently described. 



31. Berzelius informs us that " Cronstedt used but three reagents — basic 

 carbonate of soda, borate of soda, and the double salt of phosphate of soda 

 and ammonia. These reagents are still in use; and among the great number 

 of those which have been tried since that time, not one has been found to re- 

 place either of these. It is singular enough that in the very beginning of 

 the art, the very best reagents should have been hit upon." (Berzelius 

 on the Blowpipe, p. 32.) 



32. One of the objects of this paper is to attempt to show that the two 

 last fluxes mentioned in the above paragraph are not only not " the very 

 best reagents," but that they have, by the complicated and obscure results 

 obtained necessarily from their compound nature, seriously retarded the 

 progress of pyrognostic examination. For instance, speaking of the third 

 flux mentioned, the metaphosphate of soda, produced from what is com- 

 monly called microcosmic salt, Berzelius says (p. 39), "its efficiency as a 

 reagent depends principally on its free phosphoric acid ; and it is preferred 

 to this because the phosphoric acid cannot be kept without deliquescing, 

 while at the same time it is much dearer, and is also easily absorbed by the 

 charcoal. The salt of phosphorus shows, therefore, tli2 action of an acid 

 upon the substance to be tested." 



Phosphoric Acid (Symbol P). 



33. Now, if glacial phosphoric acid be heated until it melts into a sub- 

 stance of viscid or gum-like appearance, and be thus poured hot into a wide- 

 mouthed stoppered bottle (which should also be hot when receiving it), it 

 can not only be kept without deliquescing, but, when solidified by cooling 

 in the bottle, may be carried about in the pocket without fear, kept for 

 years in the most rainy climate, and allowed to remain even for hours with 

 the stopper of the bottle off. It has also the great advantage of being now- 

 a-days far more easily procured pure enough for the purpose from most re- 

 spectable chemists even in out-of-the-way stations, as in India, in conse- 



