e 
Botanical Communications. 313 
pos. current in platinum, gold, silver, copper, nickel, 
[ ) 
yoaieiuee | (Law. caloric and-+- moving together.)—neg. me- 
4 
temperature 
developes a 
tals. 
neg. current, in tin, lead, zinc, iron, mercury, arsenic, 
antimony, bismuth, (Law. calorie and +< moving in 
| opposition)—pos. 
In other words, increase of heat may be supposed to make 
the first group of metals neg. and therefore to diminish the attrac- 
tion for oxygen, chlorine, &c., while the metals of the other group 
become more pos. by this operation and thus admit readily, of oxi- 
dation, &c. It is not known whether these relations ever change at 
high temperatures; as often happens during the contact of dzsumt- 
lar metals. 
_ 2nd. Table,—shewing the order indicated by siMPpLE FRICTION of 
dissimilar metals, at the ordinary, temperature. Contact, it has 
been stated furnishes directly opposite results. ‘The series commen- 
ces with the metals that are regarded as being most negative, because 
they transmit a pos. current when rubbed against any of those that 
follow them. 
(Negative) bismuth, nickel, gold, platinum, silver, copper, mercu- 
ry, lead, tin, iron, zinc, arsenic, antimony, (positive. ) 
I avail myself of the opportunity which this notice offers of ma- 
king known to your medical readers that, by simply increasing the 
coil and observing the arrangement which I have already described 
in the last number of this Journal, I have succeeded in giving shocks, 
with the magnet, so powerful that they can scarcely be taken through 
the arms and shoulders without great inconvenience. ‘They exactly 
resemble, in roughness and celerity, those from a leyden jar and are 
superior to any from a galvanic battery. As this new instrument is 
always active, powerful and portable, Tam induced to offer it strongly 
to the notice of the medical electrician, as a substitute for the com- 
mon electrical machine. 
Art. Vil— Botanical Communications ; by H. B. Croom, Esq. 
I. Account of a new species of Plant. 
Malva * nuttalloides, (or Nuttallia * ambigua ? ) 
Plant herbaceous, prostrate, one to two feet long; stem hairy ; 
petioles long (5—6 inches) hairy ; leaves digitate, lobes from 3 to 5, 
