1872.] Capt. W. A. Ross on Pyrology, or Fire Analysis. 467 



the "earths " it is evidently only those forming carbonates which produce 

 them), or (c) to some law or principle as yet not fully known. 



76. A bead of pure boric acid is evidently more fluid in H. P. than in 

 O. P., and the hydrated appearance of cobaltine balls in the former (para- 

 graph 73) would seem to suggest the setting free of some constitutional 

 water (?) 



Phosphate of Lime. 



77. This is a useful flux for purposes of mere solution, as referred to in 

 paragraph 39. A curious phenomenon results from the application to the 

 hot glass, containing a metallic oxide in solution, of carbonate of soda, 

 which, instead of fusing in the glass under O. P., does so by itself at first, 

 apparently drawing or precipitating the metallic oxide to itself. If a hot 

 glass of phosphoric acid be applied to warm calcined lime, the mixture 

 takes fire and burns with a very pretty pale yellow light, phosphate of lime 

 being formed. This flux has been little investigated for pyrological pur- 

 poses, having been thus first used by the writer. 



Quantitative Analysis by e< Glasses" or "Beads." 



78. For this purpose it is evident that the glass must not only be weighed 

 but measured ; for, as both phosphoric and boric acids lose weight and 

 substance in direct proportion after a strong O. P., some means of measuring 

 the diameter of the bead, and of thus keeping it up to the mark, is required. 

 Sufficient accuracy for this purpose seems to be afforded by a simple instru- 



Fig. 5. 



ment as that shown in fig. 5, representing a common glass tube which 

 exactly covers a 50-mgr. bead of phosphoric acid. The graduations on 

 the outside of the tube are for the purpose of showing the length of the 

 platinum wire (in tenths of an inch), which of course is proportional to its 

 weight, the thickness or diameter being the same. 



79. Fig. 6 represents the instrument with which the platinum wire is 



2 m 2 



