210 



Mr. F. Guthrie on Salt Solutions 



1 ice at -15° with 04 HC1 sol. at 

 1 » 0° „ 0*4 „ M 



0°gave -28°. 

 15° „ -27°. 



15 c 



0'4 



-12 c 



-27°. 



All these numbers are sufficiently near to — 26°, the number 

 got when both ingredients are at 0°, to justify the conclusion that 

 the temperature of the ice has something, but little, to do with 

 the temperature of the freezing-mixture. And it appears that 

 the temperature of the HC1 solution is also without effect, pro- 

 vided that the saturation has been effected at the same tempera- 

 ture and pressure. The water acts, indeed, here much as the 

 water of crystallization acts in the case of solid salts. 



§ 55. Table of Freezing-mixtures. — In the following Table 

 the lowest attainable temperature is given. This, as we have 

 seen, is independent of the temperature of the salt and its degree 

 of crystalhydration. The temperatures are got on mixing the 

 salt with three to six times its weight of ice in lumps of the size 

 of a pea downwards. The salts are arranged according to the 

 degree of cold they furnished. 



•{ 



NaBr . . 



NH 4 I . . 



Nal . . . 

 CuCl 2 .... 



KI 



NaCl .... 

 MgCl 2 + 6H 2 . 

 SrCl 2 +6H 2 . 

 2NH 4 , S0 4 . . . 

 NH 4 Br. . . . 

 NH 4 N0 3 . . . 

 NaN0 3 . . . . 

 NH 4 C1. . . . 

 FeCl 3 (commercial) 

 Ca2N0 3 +4H 2 0. 



KBr 



A1C1 3 in strong sol. 



Table IX. — Freezing-mixtures. 



°C. 



28-0 

 27-0 

 28-0 

 26-5 

 24-5 

 22-0 

 22-0 

 20-5 

 18-0 

 17-5 

 17-0 

 17*0 

 16-0 

 16-0 

 16-0 

 14-0 

 130 

 130 



KC1 



K Cr0 4 . . . 

 BaCl 2 + 2H 2 . 

 Sr2N0 3 . . . 

 MgS0 4 + 7H 2 . 

 ZnS0 4 +7H 2 . 

 KN0 3 .... 

 Na 2 C0 3 . . . 

 CuS0 4 +5H 2 . 

 FeS0 4 + 7H 2 . 

 K 2 S0 4 .... 

 K 2 Cr 2 7 . . . 

 Ba2N0 3 . . . 

 Na 2 S0 4 + 10H 2 O 

 KC10 3 .... 

 A1NH 4 2S0 4 +12H< 

 HgCl 2 . . . . 

 NH 4 C0 2 . . . 



°C. 

 -10-5 

 10-2 

 7-2 

 6-0 

 5-3 

 50 

 30 

 22 

 20 

 17 

 1-5 

 1-0 

 0-9 

 07 

 0-7 

 04 

 02 

 0-2 



O 



We shall study this Table in connexion with the te 

 and molecular ratios of the cryohydrates of the same 



mperature 

 salt. 



Cryohydrates. 

 Cryohydrates of the Halogen Alkalies. 

 § 56. As was anticipated in § 31, the study of the nine salts 



