402 Mr. Coathupe's Experiments on the Products 



spheric tension, to supply the necessary corrections in an 

 easy and sufficiently practical manner. 



The experiment and results were as follows : 



The stop-cocks being firmly screwed into the brass caps, 

 each in its own place as marked previously to the graduation 

 of the tube, and both plugs turned for the free admission of 

 air, the one extremity was immersed in lime-water and the lips 

 were applied to the other ; then gently sucking the air from 

 the tube until the lime-water had reached within 4 or 5 inches 

 of the upper extremity, the upper stop-cock was closed, and 

 subsequently the lower one. 



The lower surface of the lime-water appeared between the 

 divisions 36 and 37. Now opening the upper cock to re- 

 lieve the tension, closing it again and opening the lower 

 cock, a small quantity of the lime-water escaped, after which 

 the lower cock was closed, and the lower surface of the lime- 

 water appeared between the divisions 38 and 39. 



By repeating these alternate restorations of the tension ex- 

 ercised upon the air included within the tube, the following 

 results were obtained, taking in all cases the nearest approxi- 

 mation to either 4ths or 3rds of a whole division. 



Table of Tension. 



Barometer 30-2 inches. Thermometer 48° Fahrenheit. 



1st, air under tension. Air under subsequent tension. 



*37*5 parts became after relieving! „q,^ ^difference 



tension j -^ "^ F r- 2. 



do. 

 do. 



^^' T" ^. T' )- 2-25 



do. 

 do. 

 do. 



do. 58- do. > 2-5 



do. 

 do. 



From 63 to 125 the differences were three divisions or parts, 

 upon each remission, and subsequent restoration of tension ; 



— from 125 to 130^, the differences were 2-75 parts each ; 



— from 130-5 to 138, they were 2-5 parts, do. 



— from 138 to 145, they were 2-33 parts do. 



— from 145 to 15J, they were 2 parts do. 



• From the graduation stated as 375 parts, to the terminating orifice 

 of the lower stop-cock, the column of lime-water measured 21*25 inches. 

 From plug of upper stop-cock to 37-5° = 6'25 inches. 



