44 REPORT — 1866. 



ascended the lieiglit of 2000 metres, witli au evacuation of uvea which, converted 

 into muscular substance, did not represent more than half the actual energy ex- 

 pended in the ascent. The author pointed out as the main objections to this 

 experiment (1) that the period of production of urea is not necessarily the period 

 of its elimination ; (2) that when starch and fat are used as food alone, the nitro- 

 gen of the alvine dejections, usually only one-twelfth that in the urinary secre- 

 tions augments so much as sometimes to be equal in amount to the latter. With 

 respect to the first objection, E. Smith has shown that lowering of the barometer 

 and thermometer retards the evacuation of urea, and these conditions were obvi- 

 ously present at the top of a high mountain. The amount of urea passed for 

 twelve hours before the ascent was 46 grammes ; but it was only 38 grammes in 

 the six hours of the ascent and six hours after it ; while it fell to 32 grammes in 

 the subsequent twelve hom'S, although a hearty meal had been taken. The result 

 was not easily explicahle on Liebig's views, that muscular force is produced by 

 muscidar waste ; but it was equally difficidt to explain on the view that the urea 

 is the mere representation of the waste of muscle due to the friction of the 

 machine, whose natural fuel is non-nitrogenous [food ; for the experiments show 

 that when the friction of the machine was largely increased by the work per- 

 formed, the amount of urea actually diminished, instead of increasing proportion- 

 allj' to the work. 



The author then entered largely into the proofs ofl"ered by experience in feeding 

 man and animals, that albuminous diet must be olfered in proportion to the work 

 demanded. lie showed that there was sufficient potential energy present in the 

 ordinary supply of albumen to men to account for the work performed. But he 

 did not deny that non-nitrogenous diet might, in the absence of such albuminous 

 supply, be temporarily used for the production of muscular force. Such vicarious 

 action is common in the body. But this admission did not interfere with the view 

 that the normal food and fuel of muscles consists of albuminous bodies, which 

 must constantly be supplied to produce sustained effort, and to prevent corporeal 

 deterioration. 



On a Nciv Process in the Manufacture of White Lead. By Petee Spence. 



On some Phenomena connected ivith the Meltinq and Solidifying of Wax. 

 By C. ToMLiNsoN, F.G.S. 



When melted bees-wax containing a small portion of a very fine powder, such 

 as that of plumbago, is poured into a shallow tinned-iron tray and allowed to cool, 

 the wax breaks up into a luxmber of hexagonal figures more or less regular, the 

 boundaries being marked by the plumbago. The fines of the hexagons are formed 

 by the mutual pressure of rings of plumbago powder thrown off" fi'om cylindrical or 

 polygonal centres of the wax in cooling. Even in deep vessels of melted stearine 

 or grease, containing particles capable of floating about in it, and of being carried to 

 and fro by currents, an in-egular network is formed by the particles arranging 

 themselves on the surface in lines. There appears to be on the sm-face a movement 

 of the gi-ease from the centre to the sides of each of these polygonal figures. The 

 figure varies with the material, and may be shown during the cooling. It may be 

 seen on castor-oil and other fatty bodies ; but not on spermaceti or crystalfine fatty 

 bodies. The figures are produced by a Idnd of local convection ; that is, convec- 

 tive currents rise and sink in various parts of the mass, so that from many points 

 at the bottom of the vessel rising currents are set up, and as the surface of the oil 

 cools bv exposiire to the air, these cooler portions snik from ^arioua points of the 

 surface", so that, instead of one central rising current, and one circumferential 

 sinking current as in ordinary cooling, many small rising and sinking currents are 

 established. Hence the surface becomes divided into many spaces, in the centre of 

 each of which a current of warm oil is rising and around the circumference of 

 which the cooler oil is sinking. Each of these S3'stems tends to fonn a cylinder, 

 with a rising central and a sinking circumferential current, and the contact of the 

 boundaries of such cylinders produces a series of polygon-shaped systems. _ If the 

 surface be veiy stiU, and there be no tendency in the oil to crystallize as it cools, 



