H4" PECULIAR VEGETABLE PRINCIPLE IN COFFEE. 



Particular de- globe, or pearl-fhaped veffel, is blown from a piece of barom*- 



fcnption of the ter tu b e an( j ; s conne & ec l j n the focket by fealing wax (or lac), 



conftruction of . J 



the lamp. which is infoluble in oil. Citizen Carccl found a great diffi- 



culty in preventing the leakage of the oil to the w#rks, which 

 he has obviated by filling the glafs veflel r with molafles thick- 

 ened by heat. This fluid is not a£ted on by oil, and anfwers 

 the purpofe very well, without impeding the motion. 



Fig. 5. Elevation of a chandelier to which the mechanifm 

 is adjufted. G, the foot containing the movement : H, refer- 

 voir containing oil, and the pump : I, the liera of the chan- 

 delier, forming part of the refervoir, and traverfed by the tube 

 of afcenlion o, which fupplies the wick with oil : K, the appa- 

 ratus of the lamp, having apertures through which the air en- 

 ters. Fig. 6. Another more elegant figure propofed by C. 

 O'Reilly. 



The number of the wheels are as follow : Barrel wheel, 108 

 teeth : It drives a pinion of 12 on the arbor of e, which has 84- 

 teeth. The middle wheel E has 96 teeth, and a pinion of 12. 

 The crank wheel has 90 teeth and a pinion of 8. The lafl or 

 endlefs (crew wheel has 20 teeth, and a pinion of 12. And the 

 fcrewhas two threads. 



The movement will go twelve hours without winding wp. 

 The ufe of the lamp is fimple and eafy. The wheel- work is 

 either locked or fet at liberty at pleafure by a ftop. In the 

 regular procefs, the wick is to be firft trimmed ; then the me- 

 chanifm is to be wound up ; and in the next place, the oil is to 

 be poured in. When the ftop is difengaged, the oil is feen to 

 rife up to the wick, and this is the proper time to light it. 

 When it is no longer wanted, the movement is to be flopped 

 of courfe, at the fame time that the lamp is extinguished. 



XI. 



Note upon a peculiar vegetable Principle contained in Coffee. By 

 Richard Chenevix, Efq. F. R. S. M. R. I. A. From 

 the Author. May 2%, 1802. ' 



Coffee heated in J[n a veffel calculated to confine the vapour of water, I 

 Se? anlTevapo- healed a confiderable portion of that liquid upon about a 

 rated, pound of raw coffee imported directly from Martinico, and 



of 



