502 



Frederick Guthrie on some Thermal and 



Fisr. 3. 



solution decomposable by heat. Water saturated with ether 

 at a given temperature, and heated in a closed tube a few 

 degrees, becomes visibly milky. When such a solution is 

 heated to 100° C, the ether, probably nearly anhydrous, forms 

 a distinct layer on the top. It is redissolved on cooling. Now 

 in § 104 it was shown that ether united with water. In 

 § 274 it will be shown that such union is accompanied by the 

 liberation of heat and by contraction. Here we have the 

 third term of such relationship, namely, the decomposition of 

 the combination by a rise of temperature. 



§ 264. Alcohol and Bisulphide of Carbon. — It may be 

 recalled that in §§ 207-228 strong, almost perfect, analogies 

 were established between water-salt alloys and salt-salt alloys. 

 So, now, I am led to consider the case of the mixture of two 

 liquids neither of which is water. And in choosing for my 

 first experiments alcohol and bisulphide of carbon, I was 

 guided by the fact that, speaking from a chemical point of 

 view, we should not expect there to be any relationship, and 

 because both liquids can be got in a state of very great purity. 

 The alcohol was obtained by distilling the nominally " ab- 

 solute " from quicklime. The bisulphide was washed with 

 water and distilled from oil of vitriol. A 

 preliminary experiment showed that expan- 

 sion resulted on mixing the two. A quill- 

 tube about 4 feet long was closed at one end 

 and half filled with the bisulphide ; about an 

 equal volume of alcohol was added. The 

 tube was closed and the contents mixed. 

 When the whole had resumed the air-tempera- 

 ture, a permanent lengthening of the column 

 of about 11 millim. had taken place. 



For exact determination the following 

 method was employed. Two bulbs, A and B, 

 nearly equal, were blown on a piece of ther- 

 mometer-tubing of rather large bore (about 

 1 millim. internal diameter), the neck be- 

 tween the bulbs having the same width and 

 being as short as practicable; the bulbs being 

 weighed, bisulphide was introduced through 

 a very fine capillary tube, until the lower 

 bulb was filled at 17°* 6. The whole was 

 again weighed. The upper bulb and the 

 lower part of the stem being filled with 

 alcohol, the height /was noted at which the 

 liquid stood at 17°*6. A third weighing 

 followed. On tilting and frequently inverting, the two could 





