SCO Mr G. Merry wcatlicr's Account of a Plathui Lamp. 



stnicted of tin, in the body of which is the reservoir, large enough to contain 

 ft quart of alcohol ; the bottom of the interior of the reservoir is concave, in 

 order that the cotton-wick may take up the last drop of the spirit. After the 

 wick has been spread in the form of a coronet at the top of the lamp, the 

 platina wire cage, containing one piece of spongy platina, is to be pricked in- 

 to the centre of the wick, and to be kept nearly in contact, but not to touch 

 it. Aft^r the reservoir has been filled with alcohol, the wick is to be inflamed, 

 and a minute afterwards, the spongy platina will have become incandescent, 

 when the flame is to be suddenly blown out, and the glass cover to be imme- 

 diately placed over the platina. Without any further care or attention, the 

 platina ball will keep ignited for thirteen or fourteen days and nights. A 

 similar apparatus has been kept ignited for this period in the University of 

 this city. If a tube is connected with a reservoir (containing a suflBcient 

 quantity of alcohol), and the bottom of the reservoir of the lamp, I have no 

 hesitation in saying that the platina ball may be kept ignited for years, as 

 the spongy platina does not appear to be in the least deteriorated by being 

 ke})t in a state of constant ignition. 



I had a similar lamp made, on a small scale, to keep ignited from eight 

 to ten hours, which affords suflicient light to shew the face of a watch in 

 the dark of night. It causes no annoyance from a glare of light. If a 

 light is required, the glass cover is to be elevated, and the platina, gently 

 touched with a match of oxy-muriate of potassa, which will be instantly in- 

 flamed ; and it is no small recommendation, that there is not the least danger 

 to be apprehended from fire. 



There have been two objections to this lamp, which \tete formidable ones, 

 namely, the expense of the alcohol, and the odour which is diffused through 

 the apartment in which it is placed. As a remedy for the first, I find by ex- 

 periment, that equal parts of alcohol and whisky answer quite as well as pure 

 alcohol ; or every one-third of alcohol and two-thirds of whisky do very well, 

 which I find, on calculation, to cost about one penny for eight hours. As a 

 remedy for the second objection, I have contrived an apparatus for condensing 

 the vapour, of which I have made a drawing. In order that it may be cor- 

 rectly understood, I have represented it as transparent ; but the apparatus 

 is made of tin, which is to be suspended from a nail in the wall. Fig. 4, G. The 

 glass tube of the lamp is to be inserted into the tin tube of the condensing appa- 

 ratus, which will completely destroy the strong odour of the vapour. The 

 liquid is drawn off by the stop-cock at the side of the condenser, which will 

 be found a compound of water, acetic acid, and seme other peculiar ingre- 

 dients giren to it by the platina. 



We may add, that this lamp may prove very useful in all mining districts, 

 as a constant light that may be depended upon, if the reservoir is periodically 

 replenished. If this should be the result, I shall feel myself amply repaid 

 for all the pains I have taken. 

 Edikburoh, March 5. 1831. 



Explanation of Figure of Platina Lamp in Plate V. 



Tig. 3. A, Vent for the vapour. B, Glass cover. C, Platina ball. U, 

 Cotton wick. E, Holes for admission of air. F, Reservoir. J>d 



