392 Intelligence and Miscellaneous Articles. 



This limit to the number sought is eleven times as great, and that 

 for the distance d half as great as that found by Dupre. We readily 

 see moreover that the limit for N may be put higher, if we assume 

 that the quantity of electricity e is distributed on the surface of each 

 of the atoms of which a molecule of water consists. The same re- 

 sult is obtained from the consideration of other more easily decom- 

 posable bodies ; and the same calculation made for oxide of silver 

 (AgO) shows that the limit for N may be put twenty-seven times 

 as great, and that for S one-third as great, if it be assumed that the 

 molecule of silver oxide contains two atoms, and that an equivalent 

 of silver oxide consists of the same number of molecules as an equi- 

 valent of water. 



It seems remarkable also that while the quantity of electricity e of 

 a source of electricity P performs the work Pe, in a molecule with 

 the same quantity of electricity e and the same tension P only half 

 this quaniity of work (that is, ^Pe) is present as work when it passes 

 from the tension P to 0. It is possible, therefore, that the amount 

 of the work of the electricity may disappear for chemical action to 

 the extent of one half to occur in another form (as heat). — Pog- 

 gendorff's Annalen, No. 8, 1870. 



EASY PREPARATION OF A LIQUID FOR PRODUCING PLATEAU^ 

 FIGURES. BY RUDOLPH BOTTGER. 



For producing these figures, as well as for the formation of soap- 

 bubbles which last for hours and have the most magnificent play of 

 colours, a liquid may advantageously be used which is readily and 

 quickly prepared in the following manner. 



In a pretty large flask parings of palm-oil soap are placed along 

 with cold distilled water, and a solution as saturated as possible pre- 

 pared by constant agitation. This is filtered through porous grey 

 paper, and is mixed with about a third of its volume of chemically pure 

 concentrated glycerine. Each time before using, it is convenient to 

 agitate it gently. By the aid of a small glass funnel about 2 inches 

 in diameter, provided with an india-rubber tube, soap-bubbles of un- 

 usual permanence and continually varying splendour of colour may 

 be prepared, provided that immediately after their production they 

 are carefully deposited upon a slightly oxidized iron ring moistened 

 with the soap solution in question. Bubbles of 1 foot diameter, and 

 more, last, when suitably protected against agitation and draught, 

 frequently for five, or even ten minutes ; others of 2 or 3 inches dia- 

 meter for hours, in most cases as long as ten, sometimes twenty 

 hours. — Poggendorff's Annalen, No. 8, 1870. 



