Mr. F. Guthrie on Salt So!utio?is and Attached Water. 



And it is seen that the greatest abasement of temperature occurs 

 when there is about 40-60 of salt to 160-140 of water (say 25 

 percent, of salt). This result is what we should expect, remem- 

 bering that the saturated solution contains 26*27 per cent, of salt. 



Table II. — Maximum Cold produced on mixing Salt and Water 

 in different proportions by weight. 

 Temp, of salt = 20°*2 C. 



Water, in 



NaCl, in 



Temp, of 



Temp, of 



Fall. 



grams. 



grams. 



water. 



mixture. 











o 



190 



10 



191 



180 



10 



180 



20 



18 4 



170 



1-4 



160 



40 



184 



16 4 



20 



140 



60 



18-4 



163 



21 



120 



80 



18-4 



165 



1.-9 



1(10 



100 



18-5 



167 



18 



§ 7. Specific Gravity of Brines of various strengths. — The 

 question as to the source of cold when brines are diluted can be 

 conveniently approached from an examination of the density of 

 brines of different strengths, and the comparison between the 

 observed specific gravities and the theoretical specific gravities, 

 supposing no change of volume to take place. The brine was 

 found to have a specific gravity of 1*2011 at 26° C, the tempe- 

 rature -at which the determinations were made. In Table III. 

 the columns 1 and 2 give the weights in grams of the quan- 

 tities of water and saturated brine. Columns 3 and 4 give 

 the percentage of the water and NaCl in the resulting brines. 

 Column 5 gives the specific gravity found, and column 6 gives 

 the specific gravity calculated under the hypothesis that no alte- 

 ration of volume ensues. 



Table II] 



. — Specific ( 



iravity of Brines of various 



strengths. 



0) 



(2) 



(3) 



(4) 



(5) 



(6) j 



Water, in 



Saturated brine, 



Water, 



NaCl, 



Observed 



Calculated 1 



grams. 



in grams. 



per cent. 



per cent. 

 26-27 



spec. grav. 



spec. grav. j 







00 



73-73 



1-2011 





60 



140 



81-61 



18-39 



11087 



11328 



70 



130 



82-92 



1707 



1-0963 



11211 



80 



120 



84-24 



15-76 



10874 



1-1117 



90 



110 



85-55 



14-45 



1*0800 



11014 



100 



100 



8687 



1313 



10725 



1 0914 



110 



90 



88-29 



11 82 



10650 



1-0815 



120 



80 



89-49 



10-51 



10574 



1-0718 



130 



70 



90-81 



919 



10501 



10621 



140 



60 



9212 



7-88 



1-0428 



1-0530 



150 



50 



93-43 



657 



1-0357 



1-0431 



160 



40 



94-75 



5-25 



10284 



10347 



170 



30 



97-06 



3-94 



10246 



10258 



