1896.] P. C. Ray— On Mercurous Nitrite. 5 



Whenever the mercury separates out as fine g^ej powder it is difficult 

 to collect the whole of it into globules ; during the decantation of the 

 liquid a part oF it is carried off, and during the process of boiling 

 with hydrochloric acid to induce coagahation another portion is lost by 

 volatilisation. As Fresenius himself lemarks : " in general a little 

 mercury is lost." In analysis (5) the percentage of mercury in the ic 

 salt is a little too high, because this was estimated as HgS (see ante 

 p. 4). It would be safe to take 30"7 as the percentage of mercury 

 both in the " free " state as well as in the ic salt, and this number has 

 been actually taken in calculating the percentage in (2) and (4). 



B. Edimation of Nitrogen. 



The salt was boiled witli water and after separation of " f fee " 

 mercury, the clear liquid was made up to a definite volume and gene- 

 rally 4 c.c, of it treated in the nitrometer. In the case of Yerj dilute 

 solutions of alkaline nitrites and nitrates it is generally the custom to 

 take a larger volume of the liquid, evaporate it to dryness and then 

 dissolve the residue in the minimum quantity (say 2 c.c.) of water. 

 But unfortunately this could not be done in the present case, as thereby 

 insoluble basic salts were formed. In dealing with small quantities 

 any experimental errors would no doiibt be highly magnified and thus 

 tend to vitinte the result; but the method is one which admits of 

 I'igorous exactitude, as was proved by blank experiments with dilute 

 solutions of protassium nitrate.* 



Preparation IV. (a) Sabstance=0"2554 gram.; Volume of solution 

 = 65 c.c. 



4 c.c. Sol. = J '5 c.c. NO ; t = 33°C ; p = 760 mean (mean of 4 cocor- 

 dant estimations). Whence NO — jr46 per cent. 



(6) Substance = 2008 irram. ; Vol. of Sol. = 226 c.c. 

 4 c.c. Sol. =3"5 c.c. NO (mean of 3 estimations) ; t = 31° C ; p = 

 760 m.m. 



Whence NO = 11-87 per cent. 



(c) Substance = 2-299 gram. ; Vol. of Sol. =234 c.c. 

 4 c.c. Sol. =3-9 c.c. NO (mean of 4 estimations) ; t = 32^C ; p = 

 760 m.m. 



Whence NO =11-93 per cent. 



* One who has made the estimation of nitrites and nitrates almost his life- 

 long study testifies as regards the Crutn-Frankland process, " that in the absence 

 of organic matter and with proper manipulation in the shaking tube, the method 

 is one of great iiccuracy, and capable of determining extremely small quantities of 

 nitrates or nitrites." Warington— Chem. Soc. Jour. 1879, page 387. 



