Berzelius on the Use of the Blow-pipe. 323 



results, it is always satisfactory as well as instructive to trace 

 the steps by which he arrives at them ; and hence it is desirable 

 that they should be detailed in the plainest possible form, and 

 when the subject will admit of it, and it does not involve tedious 

 and periphrastic operations, by the method of common arith- 

 metic. Now every one of the calculations in the notes to this 

 paper, might just as well have been worked by the common rule 

 of three, as by algebra. For instance, let us take the first cal- 

 culation. Atmospheric air is constituted by bulk of four vo- 

 lumes of azote, and one volume of oxygen, " and if we con- 

 sider the atom of oxygen as 10, and the atom of azote as 17.5, 

 it will be found to consist by weight of one atom of oxygen and 

 two atoms of azote, or per cent. 



Oxygen . 22.22. 



Azote 77.77. 



From these data the specific gravities of oxygen and azote, 

 (atmospheric air being 1.000) will be found to be. 



Oxygen 1.1111 



Azote 0.9722" (An. Ph. vi. 322.) 



To which the following formula is subjoined. 



Let X = sp. gr. of oxygen. 22.22 = a. 

 y zz sp. gr. of azote. 77.77 = b. 



Then i+il _ 1 

 5 — 



And X [ 4y::a : b. 



4 a y 

 Hence 5 — 4 y = — r— 



Andy= , ^,\, = 0.9722, and X =5- 4 y = 1.1111. 



'' 4 a -f- 4 



Now since there are five equal volumes of gases in the mix- 

 ture, which together compose the atmospheric air whose spe- 

 cific gravity is unity, the specific gravity of each of the compo- 

 nent gases must be in the ratio of the weight of one volume of 

 either of them respectively, to that of^J^th of the volume of the 

 compound produced; for there is no change of volume on their 

 being mixed; that is, calling the volume of air produced 100. 



20 : 22.22, ^c.:: 1.00 : l.llii 

 and 20 : 19.44, Sfc. ( 77.77 ) :: 1.00 : 0.9722. 

 4 

 And so for the other calculations of the specific gravity of hy- 

 drogen, chlorine, <5c. 



