Vrcparailon of Howard's Fiilminat'mg Meramj. 160 



ficicnt for most operations in chemistry ; and the ceconomy 

 in time and fuel is extreme, since a furnace of the given di- 

 mensions will ver}' well raise to the above point of heat ia 

 from five to ten minutes a Hessian crucible of such a dia- 

 meter, that the average thickness of burning fuel around its 

 bottom is not more than one inch and a half. A smaller 

 crucible will take a higher heat, but at the risk of its soften- 

 ing and falling in by the weight of the incumbent fuel. 



Coak, or conunon cinders taken from the fire just when 

 the coal ceases to blaze, and broken into vcrv sniall pieces, 

 with the dust sifted away, form the best fuel for the highest 

 heat. A light spongy kind of coak, formed of a mixture of 

 coal and charcoal, called Davey's patent coal, also answers 

 extremelv well. Charcoal alone has not weight enough, 

 when broken so small as it must be to lie close in this little 

 lire-place, to withstand the force of the blast when \trf 

 violent. A bit of lighted paper, a handful of the very 

 small charcoal called in London small coal, and ten or a 

 dozen strokes of the bellows, will kindle the fire in almost 

 as manv seconds. 



Various little alterations and arrangements, which will 

 readily occur to the practical chemist, will fit this little ap- 

 paratus for distillation with an earthen retort, heating a 

 gun-barrel passed through the fire, bending glass tubes, &c. 



I shall only add, that the dimensions of this furnace were 

 dctcniiined merely by the circumstance of having at hand 

 pieces of black-lead pots of this size, so that doubtless they 

 may be varied without any diminution, and probably w-ith 

 some increase of the eft'ect. The same mav be said of the 

 number of holes ; for in another instance four appeared to 

 answer as well as six, — with this difference, however, that, by 

 long working, the melted slag of the coak will now and then 

 partially block up one or two of the holes ; on which ac- 

 count perhaps the greater number is preferable. 



1 remain gincerely yonrs, 



0. R. AlKIN. 

 Brna<^$trcct Buildings, 

 Nov. ao, i?03. 



XXMir. On the Preparation of the Fvlm'inating Mcratrif 

 of Mr, llowAUD, I'lj ]\lr. A. S. Buukitt. 



To Mr. Tilloch, ■ ■ 



DKAR Sin, 



llAViNO at various times prepared the fulmin,ating mer- 

 turj of Mr. Uowiud, I was desirous to collect the gai» 



whici\ 



