Sir.T. D. Lauder on the Tutenag and White Copper of China. 01 
I next tried spiral coils of platinum and steel , of various dia- 
meters, and found that they were ignited, though curvilinear, 
in the same manner as if the wires were not curved. 
The preceding experiments seem to prove, that the caloric de- 
veloped in galvanic action, has no relation with the medium 
in which the ignition takes place; and that it is evolved in 
some inverse ratio of the conducting properties of the uniting 
wire. 
The phenomena of ignition in links of various metals united 
into a chain, seem connected with the passage of a material agent 
through them, displaying its powers in greater or less ignition, 
according as the passage is interrupted, or its fire more or less 
retarded, and, of course, as the amount of the resistance. 
The agent or agents, therefore, developed in transitu from 
pole to pole, will therefore swell into ignition, if the conduct- 
ing power of the medium traversed is low, or even burst its me- 
talline confine, and expend its impetus in all the brilliancy of 
an intense combustion. 
The gold, platinum and copper wires were T J^th inch in dia- 
meter ; and the steel the finest harpsichord-wire. 
Art. XVI. — Observations on the Tutenag and White Copper of 
China . By Sir Thomas Dick Lauder, Bart., F. R. S. E. 
Dear Sir, 
I observe in the last Edinburgh Philosophical Journal, an 
account of “ The analysis of Tutenag, or the White Copper of 
China,” by Dr Fyfe. That ingenious chemist remarks, that 
very different statements have been given of the composition and 
origin of Tutenag ; but it appears t*o me, that these seeming dis- 
crepancies may have arisen from the promiscuous use of these 
names given to two substances which are in reality perfectly dis- 
tinct. 
An intelligent friend of mine, who was employed for many 
years as captain of a vessel in the trade between China and In- 
dia, happening to be with me at present, I am enabled to state, 
from him, that the substance analyzed by Dr Fyfe is not Tutenag, 
but White Copper, the properties of which are totally different. 
