Mr. R, Phillips on the Electricity of Condensation. 103 



I. Oxygen. II. Oxygen, 



CuO .... ^S-ie 9-71 46-59 9-40 



SO^ .... 15-38 9-21 14-12 8-45 



HO .... 23-06 20-49 23-06 20-49 



Matters insoluble! ^ ,,_ 



in dilute N05 _f ^ ^^ 



98*30 98-36 



Hence the following empirical formula, the iron being omitted 

 as accidental. 



6CuO, AP 03, 2S0^ 12HO. 



Calculated from this formula, the composition is — 



(CuO=39-71, APO3=51-44,SO3=40-12,HO=9). 



CuO 49-85 



AF03 .... 10-76 



S03 16-78 



HO 22-59 



99-98 



The results of the preceding analyses agree very well with 

 each other and with the composition deduced from this for- 

 mula, when it is considered that different parts of the specimen 

 were operated on, that the quantities employed were neces- 

 sarily very small, and that it was impossible to separate per- 

 fectly ihe extraneous matter, consisting of brown (Fe^ O^) 

 and white particles (probably basic sulphate of alumina). 



I have not attempted to deduce any rational formula, as 

 probably several might be proposed equally plausible. 



On a future occasion I hope to present the results of the 

 examination of another substance which frequently accom- 

 panies velvet copper ore. 



XII. On the connexion of the Electricity of Condensation 'with 

 Lightning and the Aurora. By Reuben Phillips, Esq,-\ 

 [Continued from vol. xxxv. p. 497.] 

 70. TT was found (48.) that by particular management the 

 J- boiler was rendered positive by the escape of steam. 

 I have since then discovered a more advantageous method of 

 producing this effect. 



71. The weight was removed from the lever of the safety- 

 valve, and the weight of the lever only allowed to act on the 



• Estimated as AP O^. 



t Communicated by the Author. 



