54 Frederick Guthrie on Salt Solutions 



These were dissolved, mixed, and allowed to evaporate till 

 crystallization just began. On cooling, solidification did not 

 begin till — 16 o, or —17°. The temperature remained for a 

 long time at —17°; and when it had reached —18°* 8 the 

 whole mass was solid. Two analyses of the remelted last crop 

 of cryohydrate were made. The solution was weighed into a 

 covered Bohemi;m-<j;lass basin, evaporated at 100° C. to dryness, 

 kept in vacuo over sulphuric acid, weighed, gently ignited, and 

 reweighed. 



grms. grm. firm. 



(a) 4-035 of solution gave 0-9505 of total residue and 0-4890 KCl 



(b) 5-817 „ 1-3725 „ „ 0-7005 KCl 



So that the percentage compositions were : — 



a. b. Mean. 



KCl . . 12-12 12-04 12-08 



NH 4 C1 . 11-43 11-55 11-49 



H 2 . 76-45 76-41 76-43 



The molecular ratios are accordingly 



KC1=0-1608, NH 4 C1 = 0-2148, and H 2 = 4-246, 



or 



or 



KCl + 1-33 NH 4 CI + 26-4 H 2 0, 



3 KCl + 4 NH 4 CI + 79-2 H 2 O. 



Since the water- worth of NH 4 CI is 12*4 and that of KCl is 

 16*61 (§ 88), we cannot look upon the compound body as a 

 mixture of the two cryohydrates; but we may perhaps regard 

 it as consisting of seven molecules of the cryohydrate of chlo- 

 ride of ammonium in which three molecules of ammonium are 

 replaced by potassium. 



The possible precision in the analysis of the mixed chlorides 

 of potassium and ammonium induced me to extend the exami- 

 nation to the intermediate crops of cryohydrates. Accordingly, 

 the dry salts being mixed as before in equivalent ratio, dis- 

 solved, concentrated and cooled, five successive crops of cryo- 

 hydrate were collected as soon as the temperature had sunk to 

 — 16°-5, the last being the mother-liquor. 



Solution 



Total residue .. 

 KCl 



Therefore 



a) 



6-6090 



1-4810 



•7870 



11-90 

 10-50 

 77-60 



(2) 



5-8765 

 1-3445 

 0-6760 



11-50 

 11-37 

 77-23 



r A 



(3) 

 4-0540 

 0-9375 

 0-4630 



7 (4) 

 6-8210 

 1-5720 

 0-7815 



(5 

 6-4720 

 1-4960 

 0-7410 



11-44 

 11-67 

 76-89 



(6) 

 5-0750 

 1-2145 

 0-5890 



kci: 



NH 4 C1 ; 



H 2 



11-54 

 11-58 



76-88 



11-45 

 11-59 

 76-96 



11-60 

 12-32 



76-08 



