4 36 Researches upon the Heat developed 



This stopper is perforated at its axis by a small vertical 

 hole, which is wlmlly closed or partly opened, when re- 

 quisite, bv means of a small vice with a copper nut. 



A small pipe about a line and a half in diameter, and two 

 inches six lines in length, issues horizontally from the 

 sides of this vase, and very near its bottom. At the 

 distance of an inch and four lines from the vase this pipe 

 forms an elbow, and afterwards ascending vertically forms 

 the beak of the lamp. 



This small pipe is very thin throughout, except at its 

 upper extremity, where it is thicker, in order to give it a 

 form convenient for receiving a very small cylindrical ex- 

 tinguisher five lines high by three and a lialf in diameter, 

 intended lo close the beak hermetically, without touching 

 or deranging the wick at the instant the lamp ceases burn- 

 ing, and to keep it constantly shut when the lamp is not 

 burning. 



Without this precaution, in experiments made with 

 ether, so great a quantity of this volatile liquid wovdd 

 escape in vapour, by the beak of the lamp, during the time 

 taken up in weighing it, that there would be no way of de- 

 termining the quantitv burnt. 



To support the beak of the lamp, it is stayed by two 

 pieces of copper wire, which proceed in a horizontal direc- 

 tion to join the body of the lamp lo which they are soldered. 



In order to keep this lamp constantly cold, as VA-ell as 

 the Iu)uid whicVi it contains, it is placed in a small tub 

 and entirely covered, excepting the extremity of its beak 

 and that of iis mouth-piece, by a mixture of pounded ice 

 and water. 



Whf-n we weigh the lamp, it is taken out of its tub, and 

 care is taken to wipe it well with dry linen before placing 

 it in the .scales. 



When the lamp is lighted, we must not forget to open 

 a little, and but a very little, the vice which forms its stop- 

 per, after it has burned t^vo or three minutes j for without 

 this precaution it n)ight ^o out. 



As the small hor!Zontal pipe, by which the liquid which 

 is burnt passes from the reservoir of this lamp to reach its 

 beak, is always filled with the liquid so as to have no com- 

 inunicaiion with the vapour of the liquid which is di- 

 eperscd in the upper part of the reservoir, this vapour can 

 no longer escape by the beak of the lamp, as it did before 

 I contrived the method of preventing it. 



If I have given a very minute description of this lamp, it 

 gjipeared to be necessary to spare those who wish to repeat 



my 



