218 Mr. Gill on a Lamp without Flame. [March, 



him, and took considerable pains himself to ascertain the proper 

 thickness of the wire (which is of considerable importance), and 

 other particulars necessaiy to its success. I informed my friend 

 Mr. J. J. Hawkins, engineer, of it, the same evening ; and he 

 mentioned it at Sir Joseph Banks's converzatione on the 25th ult. 

 to many gentlemen of the first intelligence, in point of chemical 

 knowledge ; to all of whom it was new. 



The proper size of the platina wire is the -r^th part of an inch, 

 which may be readily known by wrapping ten turns of the wire 

 round a cylinder, closely together ; and, if they measure the -ji-th 

 part of an inch, it will be right. A larger size will only yield a 

 dull red light ; and a smaller one is difficult to use. Mr. Wm. 

 Carey, optician, and Mr. J. T. Cooper, chemist, in the Strand ; 

 and Mr. Newman, Philosophical Instrument-maker, Lisle-street, 

 have been furnished by me with the accurate particulars ; and 

 will supply the platina wire, and the lamps, to any persons who 

 may require them ; as will, also, Mr. Garden. 



About twelve turns of the wire will be sufficient, coiled round 

 any cylindrical body, suited to the size of the wick of the lamp ; 

 and four or five coils should be placed on the wick, and the 

 remainder of the wire above it ; and which will be, as aforesaid, 

 the part ignited. 



I have found, by experiment, that a wick composed of twelve 

 threads of the ordinary sized lamp cotton yarn, with the platina 

 wire coiled around it, will require about half an ounce of alcohol 

 to keep it alight for eight hours. 



A slightly acid smell, rather pleasant than otherwise, is yielded 

 by this lamp during its ignition, arising from the decomposition 

 of the alcohol ; as is, also, the case with ether. 



I need hardly point out the peculiar safety this lamp will afford, 

 as not a spark of fire can fall from it. And its being totally free 

 from the unpleasant smell and smoke common to oil lamps, will 

 be additional recommendations in its favour. 



To persons who are not aware of its nature, the novel appear- 

 ance of this lamp, in its wick continuing red hot for such a length 

 of time, is very surprising ; and it may possibly lead to other 

 contrivances, which may prove of the utmost importance in 

 chemistry, and the arts. I am, Gentlemen, 



Your most obedient servant, 



Thomas Gill. 



P. S. When the wire has become oxided, it will be necessary 

 to uncoil it, and rub it bright again with fine glass paper; 

 which will cause it to act again with increased effect. 



