614 PROF. LETTS AND MR R. F. BLAKE ON 





Obtained, 



!arbon, . 



4870 



[ydrogen, 



5-63 



hosphorus, . 



17-54 



Calculated for (C 7 H 7 )H 2 P0 3 

 - 48-83 

 5-23 

 18-02 



Salts. 



Barium Benzyl Phosphinate (normal) (C 7 H 7 )BaP0 3 ,2H 2 0. — This is an extremely 

 characteristic compound, and is readily obtained by neutralising a fairly strong solution 

 of the acid with a warm solution of caustic baryta, when it crystallises out in thin plates. 

 As it is much less soluble in hot than in cold water, it is precipitated on warming a weak 

 solution, and if the heat is applied gradually (for instance by immersing the vessel con- 

 taining the solution in a water-bath full of cold water and then heating the latter) it 

 separates in large scales with the lustre of mother-of-pearl. This property furnishes an 

 easy method for identifying the acid and separating it from other substances. 



Analysis. 



1-4246 (dried at 110° C.) gave 1-0809 BaS0 4 = 0*63555 Ba = 4461 per cent. 



Obtained. Calculated for C 7 H 7 P0 3 Ba 



Barium, .... 4461 44-62 



1-3643 lost at 110° C. 0-1389 = 10-18 per cent. 



Obtained. . Calculated for C 7 H 7 BaP0 3 ,2H 2 



Water, .... 10-18 1049 



Solubility. — An excess of the salt was allowed to stand for some days with water, 

 well shaken repeatedly at intervals and the mixture filtered. Temperature of solution 

 before filtering, 9°'7 C. 100 c.c. of this solution weighed (at 9°*7 C.) 101*446 grms., and 

 left on evaporation 1*6115 grms. of the anhydrous salt =1*8005 grms. hydrated salt. 

 Therefore, at 9°*7 C, 



100 c.c. of saturated solution contain 1-8005 grms. hydrated salt. 

 100 grms. of water dissolve 1*807 „ „ 



Another quantity of the cold saturated solution was boiled for some time, then 

 filtered through a hot- water funnel and cooled to 9 C *7 C. 



100 c.c. of this solution weighed (at 9°*7 C.) 100*475 grms., and left on evaporation 

 0*3855 grin, of salt (dried at 110° C). Therefore, at 100° C. (or rather at the boiling 

 point of the solution) 



100 c.c. of solution contain (about) 0'4307 grm. hydrated salt. 

 100 grms. of water dissolve 0*4305 „ „ 



Acid Barium Benzyl Phosphinate, (C 7 H 7 . HP03) 2 Ba,3H 2 0. — This salt was obtained 

 by adding to a solution of the normal salt the calculated quantity of benzyl phos- 

 phinic acid and evaporating the mixture to a very small bulk, when, on cooling, the 

 compound separated as a crystalline mass. It is very soluble in water. 



