Botanical Communications. 313 





f pos. current in platinum, gold, silver, copper, nickel, 



T r (Law. caloric and+s moving; together.) — nez. me- 



Increaseof | \. { ° ° ' & 



temperature ^ " . . , , . 



i j ] neg, current, in tin, Jean, zinc, iron, mercury, arsenic, 



r ! antimony, bismuth, [Law. caloric and-\-s 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 disimi- 

 lar metals. 



2nd. Table, — shewing the order indicated by simple 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 



fi 



As this new instrument is 



W — 



always active, powerful and portable, I am induced to offer it strongly 

 to the notice of the medical electrician, as a substitute for the com- 

 mon electrical machine. 



Art. VII. — Botanical Communications; by H. B. Croom, Esq. 



I. Account of a new species of Plant. 



Malva * nuttalloides, for NuttalUa * ambigua 1) 

 Plant herbaceous, prostrate, one to two feet long; stem hairy; 

 petioles long (5 — 6 inches) hairy ; leaves digitate, lobes from 3 to 5, 



