145 



In the numerous distillations which were performed for the puri- 

 fication of the hydrate of cresyl, some circumstances were observed 

 which led to a suspicion that the body undergoes a change of 

 composition, either through the distillation itself, or by some in- 

 fluences accompanying it. These circumstances were, 1st. A tarry 

 residue, from a liquid which when introduced into the retort was 

 perfectly colourless. 2nd. The formation of a small quantity of 

 water in the commencement of such a distillation, though none was 

 contained in the substance used. 3rd. The gradual lowering of the 

 boiling-point of the whole liquid by a great number of distillations. 

 These facts, taken in conjunction, naturally suggested that the oxy- 

 gen of the air contained in the retort might act upon the substance, 

 and thus gradually reduce it to hydrate of phenyl. 



In order to test the correctness of this hypothesis, the atmospheric 

 air was expelled from the distilling apparatus by dry hydrogen gas, 

 and the distillation performed in a pure atmosphere of this gas. A 

 great number of distillations performed in this manner were at ex- 

 actly the same temperature, and all the other anomalies were simul- 

 taneously removed. It was however found that the liquid always 

 boiled at a lower temperature in hydrogen than in atmospheric air, 

 the difference being about 2 Cent., and this without any alteration 

 of the pressure on the surface of the boiling liquid. A similar fact 

 was noticed in the distillation of hydrate of phenyl, and also of some 

 other liquids. 



XVII. " On the Formation of Powers from Arithmetical Pro- 

 gressions." By C. WHEATSTONE/ Esq., F.R.S. Received 

 June 15, 1854. 



The same sum n" may be formed by the addition of an arithmetical 

 progression of n terms in various ways. Hence we are enabled to 

 construct a great variety of triangular arrangements of arithmetical 

 progressions, the sums of which are the natural series of square, 

 cube and other powers of numbers. Among these there are several 

 which render evident some remarkable relations. 



