146 Intelligence and Miscellaneous Articles. 



terest; the thousandth or even ten- thousandth of a foieign metal is 

 sufficient to cause verjf characteristic differences in the results of 

 parallel experiments. 



A ten-thousandth of lead added to mercury stops its distillation 

 almost entirel}'. In the following comparative experiments, the 

 mercury which distilled with the greatest difficulty was put into the 

 retort A., which yielded most quickly. 



First operation. — Retort A., containing 100 grammes of mercury, 

 to which l-10,000dth of lead had been added, yielded in a given time 

 by distillation in the bath 5 grammes of mercury. 



Retort B., containing the same quantity of mercury without any 

 lead, heated for the same time in the same bath, gave by distillation 

 67 grammes of mercury. 



Second operation. — Retort A., containing 100 grammes of mercury, 

 to which 1-lOOOdth of lead had been added, yielded in a given time 

 by distillation in tlie bath 2 grammes of mercury. 



Retort B., containing the same quantity of mercury without any 

 lead, heated for the same time in the same bath, gave by distillation 

 55 grammes of mercury. 



Zinc was substituted for lead, and when in the proportion of 

 l-10,000dth, the mercury distilled was to that obtained without the 

 zinc as 6'5 grms. to 72. 



Some metals have no sensible influence on the distillation of mer- 

 cury : among these are gold, iridium, silver, copper, tin, nickel, cad- 

 mium and arsenic. The action of platina is precisely the reverse of 

 that of lead and zinc : it accelerates distillation, but less than lead 

 and zinc retard it ; in order that platina may produce this effect, it 

 must be digested in the mercury for a day or two at the temperature 

 of 122° to 176° ¥.—Ann. de Ch. et de Phys., Novembre 1846. 



EASY METHOD OF PREPARING IODIDE OF POTASSIUM. 



M. Pypers subjects to a moderate heat a mixture of 100 parts of 

 iodine, 75 of carbonate of potash, 30 of iron filings and 120 of water. 

 The mass is to be dried, and then heated to redness ; the resulting 

 reddish powder is to be treated with water, and the solution obtained 

 filtered and evaporated to dryness. One hundred parts of iodine 

 yield 135 of very white, but slightly alkaline iodide of potassium. — 

 Journ. de Chim. M^d., Decembre 1846. 



FORMATION OF GLYCERINE. BY M. ROCHLEDER. 



If castor-oil be dissolved in absolute alcohol and a current of dry hy- 

 drochloric acid gas be directed into the heated solution, the oil under- 

 goes decomposition. When the liquor is agitated with water, after 

 the hydrochloric gas has acted for a sufficient time, an emulsion is 

 obtained, which gradually separates into two portions, one of which is 

 oily and floats, the other is watery and extremely acid ; the latter is to 

 be poured off and evaporated by a water-bath. At first hydrochloric 

 acid is disengaged, and there remains a syrupy and yellowish mass 



