Joty—On the Conservation of Mass. 39 
The result of experiment @ is a velocity conferred at end of thirty seconds from 
moment of application of magnet amounting to fifteen scale-divisions per fifteen 
seconds. The result of experiment 4 is a velocity at end of thirty seconds of 
eighteen divisions per fifteen seconds. Experiment ¢ gives at end of thirty seconds 
a velocity of 12: divisions per fifteen seconds. The mean is 14°5 divisions per 
fifteen seconds, or nearly one division per second. 
Experiment on the effect of liberating the liquid in the upper vessel by the melting of the 
Susible plug. 
The experiment (one of many similar) was made on January 14th. Water 
was placed in upper vessel and sand in lower vessel. Hour, 4.30 p.m. It will 
be seen (fig. 2) that the curve is undisturbed by the application of heat to the 
connecting tube, and that the descent of the liquid apparently produces no 
perturbation. 
Readings obtained at intervals of 15 seconds:—21, 13, 7, 4, 4,7, 12, 18, BY Mo 
36, 56, 65, 76, 87, 97, 107, 116. The sign! marks the instant in which the 
contact was depressed for the couple of seconds required to melt the plug. 
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In the following experiments, the mass of copper sulphate varied from 20 to 25 
grammes. In the earlier experiments the solvent is very dilute sulphuric acid, in 
later ones water only ; the quantities being about 26 ¢.c. where the acid was used, 
and 25 when water only was used. The weight of the glass vessel was in earlier 
results nearly 12 grammes; later one of 13-7 grammes, and finally one of 15:7 
grammes had to be used, owing to accidents. The weight of cork-dust jacket 
and paper cylinder varied at different times from 16°3 to 22°5 grammes, the 
higher values being adopted in the later experiments. The total mass varied 
between 80 and 85 grammes in round numbers. 
TRANS. ROY. DUB. SOC., N.S., VOL. VIII., PART I. H 
