Chemistry and Physies. 397 
gee until the length beoynee small compar ed with the diame- 
he law for changes in the diameter and the effect of a 
be parallel to the axis were also stadied. Finally, on the 
ground of the peculiar facts ex xamined in this memoir, as well as 
e whole of the known facts, he concludes that the present 
steel, hat in 
regard to the magnetic properties of its elements this substance 
ae be considered a heterogeneous mass.— Phil. Mag., xlix, 81, 
EB. 6. P. 
: Frictional Electricity.—M. Rossrrri has made a careful study 
of the current developed by a Holtz machine and shown that it 
follows the laws of a galvanic battery. The machine was turned 
by a weight, and the work done measured when charged and dis- 
charged. The current was determine by a galvanometer and 
the resistance by four long fine tubes filled with distilled water. 
he current is nearly proportional to the speed, but increases a 
little more rapidly than the latter. The ratio of the two alters 
ith the a 
current the machine must be driven faster in wet weather, 
although the work required is less than when the rie is dry. 
ec onomy, therefore, is greater on wet than on dry days. A Holtz 
machine resembles a galvanic battery, having an electromotive 
force and interior resistance which are constant as long as the 
velocity and moisture are constant. The electromotive force is 
n de 
oistu reases, 
The interior resistance on the other hand is independent of the 
the pipe ea force equalled 41 000 volts, while with the 
moisture °35 it equaled 57,000 volts. The resistance with a 
velocity of eight turns per second was 540, ries, 000 at and with 
a velocity of two turns 2,680,000,000 ohm The current pe 
the law of Ohm, consequently if very large axtortor resistance 
are employed, the strength - the current gives the mecha iba 
Bi See of heat. The mean of seventeen experiments gave asa 
esult the umber 428, which —— es closely with up com- 
tad gel sf ue.—Ann. de Chi et Phys., iv, 214. 
10. Che at Subse in the ' Adnaeen A desiaeton "for the 
Advanasinent - Science.—This sub-section of the American Asso- 
Ciation was organized a Sota pegs iin eps in August last. 
It is called the “ Sub-scti f Chem , Ch hemical Physies, 
b 
we come at Detroit, gt the next sein ie ra be held, in August 
of this year. We make ee statement ver willingl y at the 
