360 



Frederick Guthrie on Salt SoltUt 



This Table is to be regarded as replacing Table VI. in $ 10 

 as far as the two are comparable. I bracket the subervohv- 

 drate and the NaCl together, because the range of ratio is so 

 small for a great temperature-difference that I cannot at pre- 

 sent undertake to say within two or three degrees the tempe- 

 rature-range peculiar to each body. 



§ 128. Separation of Ice or Anhydrous Chloride of Ammo- 

 niumfrom solutions of that salt. — The following Table (XVII.) 

 shows the temperature of solidification of solutions of NH 4 C1 



of various strengths. 



Table XVII. 



NH CI 



H.,0 



Temperature 





per cent, by 



per cent, by 



Centigrade at 

 which solidifi- 



Nature of 

 solid. 



weight. 



weight. 



cation begins. 





1 



99 



o 

 - 0-4 



Ice. 



3 



97 



- 1-6 



ft 



5 



95 



- 31 





7 



93 



- 4 6 



,. 



10 



90 



- M 





13 



87 



- 99 



„ 



15 



85 



-120 





lf> 



84 



- 130 





17 



83 



-140 





18 



82 



-15 



., 



19 



81 



-158 



„ 



19 27 



80 73 



-160 



Cryohydrate. 



20 



80 



-15 



NH 4 01. 



22 



78 



- 5 



n 



23-2 



76-8 









25 



75 



+ 8 





30 



70 



+32 



» 



It will be seen that I make now the solidifying-point of the 

 cryohydrate —16 instead of —15. This agrees with its tem- 

 perature as a cryogen. The tracing of NH 4 CI in fig. 1 is 

 seen to pass through the 0° line without deflection. Like the 

 NaCl line it has a point of contrariflexure, but not so near the 

 cryohydrate as with the latter salt. The determination at 0° C. 

 was derived from the analysis, 12*1852 of the liquid gave 

 2-7721 of NH 4 CI. 



§ 129. Separation of Ice or Anhydrous Nitrate of Potassium 

 from solutions of that salt. — Nitrate of potassium being far less 

 soluble below 0° C. than the two preceding salts, and its cryo- 

 hydrate not differing much from the saturated solution at 0°, 

 I have not attempted to get any temperature-values between 

 the two ; but I have carefully followed the form of the tra- 

 cing up to the cryohydrate, and also above 0°. 



