Joty—On the Volume Change of Rocks and Minerals attending Fusion. 301 
tures consecutively. They are nevertheless, as will be seen by the curve (Plate 
XVIII.), very consistent with one another. ‘The curve is marked ‘“ Augite I.” 
At this stage of the experiments a standard method of shaping the ovens was 
introduced. The form of oven was a little altered. Some alteration was also 
made in the form of the forceps which supports the oven; these were in fact 
brought to the form shown in figure 1. These alterations necessitated a fresh 
thermometric curve. The following readings fix the course of this curve : 
Curve B. 
ston ee ee 
Sulphur, : 5 le 114°°5 99°) 
Silver chloride, 2 atsi25 451 436 
Silver sulphate, Elks’) 654 639 
Potassium carbonate, 19:2 834 819 
Copper oxide, . - 22°5 1055 1040 
Palladium, : « edhe 1500 1485 
This last point, it is true, is open to the suspicion that, as in the case of the 
platinum beads, the temperature taken up by a metal will be greater than that 
taken up by a non-conductor of heat. The error introduced in this manner may 
be as much as 7:5 per cent. 
Thermometric Curve, B. 
Mating Points and Galvanometer ae 
_ 1500° 
1000° 
Galvanometer® 
Fic. 9. 
In valuing estimates effected at the highest readings on the curve, this 
possibility must be borne in mind. They cannot claim close accuracy. The 
