OO FKVKIl. 



• ■rnH'S of lIlC illstrUllU'llt lH'' ili i nlc ill\ li ss tli.in tin- lii:il'_'ili ol" ilnri:i>r or iln li .isr 



of the lu-at lust. 



The cunn>lftf njipariitus' uliich 1 have cinpldjM'd i-oiisiNts of two parts: 1st, the 

 apparatus for aiialyziiijf tin- air of the room; *Jd, tlu' caloriimtrical apparatus projKT. 

 'i"li«' first of thrsc is counjoscd of an aspirator, nu'ter, harimn tubes, and sulpliuric 

 ucid bull)s, or ililoridf of c-aU-iuiu tubes. Tbe second (I'l. 1.) eonsisls of tin- ( alori- 

 motcr proper (a) ulrcudy described, sulphuric acid bidbs (b), tubinfj, two meters, 

 and a lar<{e and smalt air pump. \\'lien it is arran<red and workini;, the air, wimsp 

 tempcT.ilure is measured by a tlierniometer liau<,'ing near by, enters tlie calorimeti-r 

 nt X, an«l emerj^es at y; immediately after this the current is tapped l»y means of a 

 side pi)"' (z) whose end projects as a sort of nipple into the centre of the lower of the 

 larjjer tubes. Directly afterwards the main current passes over the bulb of the ther- 

 mometer (t), by the scale of which its temperature may be read. It then passes on to 

 the larj^e or "air nn-ter" (m) and out throuj,'h the air pump (p). The samplr-, imme- 

 diately after beins; drawn o>it at z, passes through tlie sulphuric acid Itulbs and is 

 robbed of its water; travelling onward it loses its carbonic acid in the tubes (l)l») 

 which contain a solution of caustic barium, finally, having registered its qiuuititv in 

 the small or "sample meter" (m'), it is drawn into the aspirating bottles (v v). It is 

 plain that the sum of the amounts registered in the large and small meters is the 

 (pnintity of the air which has in any gi\ tn time i)assed tiirougli tin; bo,\. 'I'hcrc are 

 one or two details in the running of the apparatus, not yet mentioned, worthy of 

 specific notice. It is necessary to take especial precautions that no moisture is dt*- 

 posited in the tubing before the bulbs (.s) are reached; hence tin- bull)s shoidd lie 

 placed as near as possible to the orifice (y), and the tul»es siiould be mad<' exclu- 

 sively of wood and ruldier. In order to vender the th< rnumu tt r-joint tight, nulled 

 l>araffiue should be poured into it. 



Ilefore detailing the calorimetrical experiments, it is perhaps best to give tin 

 explanation of the methods of recording and of calculation. This can i»e done 

 most clearly and briefly by presenting as an examph" the report of a portion of an 

 actual experiment.'^ 



I ip to state thai (rrcat pains had born taken to insiirr accuracy in the ii|ipnnila«. 



The nictom were "Godwin's Exporinic«itnl Meters." tested with the proatest care. The thcrmoinctcn 



I the norniiil one in tlic pliysicul Inhornlory of the Univentily ; 

 1-. iinil the recordi'd tvinperutiiros are corroi-led toinpenilures. 

 ' In this memoir, onlcM otherwise distinctly stated, the lempcratnres are accoiHlinp to the Fahren- 



'1. (<iimple, and nir meters) in cubic feel; nnd the calcium tobes 



