470 Intelligence and Miscellaneous Articles. 



internal diameter. It was filled with the liquid to be investigated ; 

 and on the top, touching the liquid, was a copper or leaden vessel, 

 into which steam was continually passed from a small steam-boiler. 

 The condensed water was reconducted into the steam-boiler. 



Four horizontal thermometers were fixed laterally in the vessel, 

 in such a manner that their bulbs coincided with the axis of the 

 cylindrical vessel. Owing to changes affecting the glass vessels, I 

 was not always able to give the fourth thermometer the same distance 

 from the third ; and I shall therefore not always give its tempera- 

 ture. The liquids to be investigated had always to be heated about 

 eight or ten hours before they exhibited constant temperature. 



Water was first of all compared with solution of chloride of sodium. 

 The heating-vessel was of copper; the first thermometer was 10 

 millims. from the side of the vessel to be heated ; the others fol- 

 lowed at distances of 60 millims. 



I. Water and chloride of sodium. 



Chloride 

 Water. of sodium. 



1st thermometer 72*4 C. 72*2 C. 



2nd thermometer 26 23'8 



3rd thermometer 20 17*9 



4th thermometer 19 17*4 



External temperature 13°. 



Forming, now, from the first three temperatures t , t v t 2 the quo- 

 tient q= ° 2 , it becomes 3* 6 for water, and 3*79 for chloride-of- 



sodium solution, from which it follows that water conducts better 

 than common salt. 



As the thermometers were so far apart that the temperatures very 

 rapidly decreased, the first three thermometers were fixed 30 millims. 

 apart. Water and concentrated solution of sulphate of copper were 

 compared. 



II. Water and sulphate of copper. 



Sulphate 

 Water. of copper. 



1st thermometer 73'2 C. 72*5 C. 



2nd thermometer 34*3 34*2 



3rd thermometer . r 22*2 22*2 



External temperature. . . . 14*5 14*5 



The quotients are 2*78 for water, 2*77 for sulphate of copper ; 

 both, therefore, conduct equally well. 



For comparing water with sulphuric acid (spec. grav. 1*25), a 

 leaden heating-vessel was used : the first thermometer was at a di- 

 stance of 14 millims. from the heating leaden surface. 



