in Comlustmi, and in the Condensuiion of Vopotirs. 2S7 



sticks of an inch square each: a border of copper, three 

 lines in breadth, which descends quite round the bottom ot' 

 the receiver, serves to attach the receiver to its wooden 

 frame by means of a row of very small nails. The body 

 of the receiver enters about one line into its frame, and 

 fills it up exactly. 



The perfection of this apparatus depend? essentially on 

 the form of the worm, as will be seen when we consider 

 the object for which it is intended. 



The products from the combustion being all elastic 

 fluids, and. consequently substances which cani^.ot com- 

 mianicatc their heal except by proceeding particle by pani- 

 cle to deposit it on the surface of the cold and imn)Oveable 

 body which is destined to receive it, it became indispensa- 

 ble to arrange the apparatus so as to make these warm 

 fluids necessarily pass under and against a large flat surface 

 placed horizontally and always cold. 



l-*revious to making use of horizontal worms constructed 

 of flat pipes, 1 had tried more than once those of the com- 

 mon form J but they never answered my purpose in a per- 

 fect manner, and I never could take any account of the 

 experinienis in which they were eniploycd. 



There is no doubt that the form which I adopted for the 

 worm of my calorimeter would be very advantageous for all 

 kinds of distilliPig apparatus. 



One thing very im])ortant in the arrangement of my ap- 

 paratus, is the form of the thermometer which I use for 

 measuring the temperature of the water in the receiver. 

 This thermometer, which I made myself ten years ago, and 

 which after undergoing many trials always apjieared good, 

 is a mercurial thermometer divided according to tlie scale 

 of Fahrenheit. It is one of four thcnnometers, all similar, 

 which 1 employed in my researches upon the cooling of 

 liquids inclosed in vessels, made at Munich during the 

 winter of IS02-3. Its reservoir, which is cylindrical, is 

 only about two lines in diameter, while it is four inches 

 high; and as the water in the receiver of my tlicrmometcr 

 is tour inches deej), this thermometer always indicates the 

 mean tenpcrature of this li(|uid, ivkulevcr may be l/w tem- 

 ptruliirei of lis dij/'ercni shut a. 



I have Ircquently had occasion, in inv difllrent researches 

 upon heat, to notice the importance of this precaution; and 

 I cannot conceive how we may expect to avoid great errors 

 in measuring the temperature of heated or cold liijuids, if 

 we iiegkct to pay attention to them. i\n- nty own part, 



I treelv 



