for the Theoretical Proof of Avogadms Law. 307 

 Let <£vV = T, <vr=(Jr, <*>?*' = 2S, <r, nC = 90° + S, 



Fig. 1. 



V y< 



Let be the angle of the planes r, v, and r, I2C; and 0' 

 the angle of the planes r*, v', and r f , I1C. I denote the sines 

 and cosines of the angles by the corresponding Roman and 

 Greek letters. For the sake of clearness I include in fig. 1 

 those lines of fig. 2 of my Theory of Gas Diffusion, just 

 mentioned, which are here necessary. Then, according to 

 formula (21) of p. 72 of that treatise, 



m v 



T-\ IIIU IIIL 



mv 



2 



2mKvr 



m + M 



(go 2 — ysao) + 

 Y2 



(m + M) 2 



(1) 



