THE BEE-KEEPERS' REVIEW, 



85 



Units. 



C = Copper 515. 



•' " Iron 293. 



" " Zinc 225. 



" " Lead 113. 



" " Marble, grey, fine grained 28. 



" " " wliite, coarse grained. . 22.4 



'* " Stone, calcareous, tine 16.7 



" " " " ordinary 13.7 



" " Glass (>.() 



" " Brick-work, baked clay 4.83 



" " Plaster, ordinary 3.86 



" " Oak, perpendicular to the fibres 1.75 

 " " Walnut, " " " " 1.4 



" " Gutta percha 1.38 



" " India rubber 1.37 



'♦ " Brick dust, sifted 1.3:5 



" " Coke, pulverized 1.29 



" " Cork 1.15 



" " Chalk, in powder 0.869 



" " Charcoal of wood, powdered. ... 0.636 



" " Straw, cJiopped 0.563 



" " Coal, small, sifted 0..'i47 



" " Wood ashes 0..531 



" " Mahoganij saw dust 0.523 



" " Canvas of hemp, new 0.418 



" " Calico,new 0.492 



" " AVriting paper, white, 0.346 



" " Cotton or sheep's wool 0.323 



" " Eider down 0.314 



" " Blottinij jjaper, (/rcii 0.247 



" " Stagnant air. ^ .\ . .'. 0.300 



" " Double windows when the glass 



is not less than 2 inches apart 3.600 



The following table is taken from a Table 

 of Thermal Conductivities in an article on 

 Heat by Wm. Thompson, in the Encyclopae- 

 dia Brittanica. Copper being a good con- 

 ductor amongst the metals, is taken at 

 nearly unity : 



Copper 0.96 



Iron 0.20 



Air 0.000049 



Water 0.002 



Fir, across fiber : 0.00026 



Wood generally 0.0005 



Cork 0.000029 



Writing paper 0.000119 



Grey paper, unsized 0.000094 



Calico, new 0.000139 



Wool, carded, all de^isities, 0.000122 



Finely carded wool 0.000111 



Eider down 0.000108 



From this table we see that water conducts 

 four times as much heat as wood, and so 

 any of the materials will conduct heat more 

 readily when wet. This table bears out 

 Cheshire's statement that air conducts near- 

 ly two and one-half times as much heat as 

 cork. Solid wood conducts about ten times 

 as much as stagnant air. 



COMMENTS ON THE MARKED PARAGRAPH IN 

 MR. DOOLITTLe's ARTICLE. 



" Numerous dead air spaces in a five inch 

 wall, etc." This is true. 



"His sawdust packing is little, if any, 

 better than a solid wall." This is a mistake, 

 assuming that the sawdust keeps dry. See 

 extract from Tyndall " The transmission of 

 heat, etc." 



Mr. D. may be correct about the superior- 

 ity of straw, not entirely on account of the 



reasons he gives, but because as Poppleton 

 puts it, its "affinity" for moisture is not so 

 great, and, if it is tightly packed, I know it 

 will retain heat better than a '^^ board hive. 

 Poppleton's article in the Sept. Review is 

 sound and in accord with the teachings of 

 Rumf ord and Tyndall. 



I think there is as much to be gained by 

 having a good transmitter (not absorbent) 

 of moisture as there is in the non-conduc- 

 tivity of the material. In this respect it 

 seems to me that cork dust is away ahead of 

 everything else available to bee keepers. I 

 have packed with it year after year and the 

 only wet stuff would be a little next to the 

 bottom board. I have one of Jones' palace 

 hives packed with 1}4 inches of Sawdust. 

 In the latter part of winter I took off the 

 bottom of the packed walls and found the 

 sawdust frozen solid about two thirds of the 

 way up. It is too much of a retainer of 

 moisture to be good. 



The finer the mechanical division of a 

 substance, provided it is not packed too 

 tight, the warmer — vide raw and twisted silk. 



Lindsay, Ont., Canada, April 9, 1890. 



What is needed for the walls of a hive is 

 some material that will gradually absorb 

 heat, but not moisture. What is needed is a 

 sort of caloric balance wheel. Something 

 that will store up the heat from the bees or 

 the sun, then gradually give up this heat 

 when there comes a cold snap or a frosty 

 night. AVe can see now why a chaff hive 

 protects the bees from the heat of the July 

 sun. It absorbs the heat during the day, 

 and gives it up at night. It will be seen 

 that water is a most excellent conductor of 

 heat ; hence the material used for packing 

 must not only be one that is a poor conduc- 

 tor of heat, but one that is also a poor 

 absorbent of water. Cork dust fills the bill. 

 If we could have hives surrounded with this 

 permanently, without making them too 

 clumsy or too expensive, we should be quite 

 inclined to give them a trial. 



Apropos with this subject of heat and its 

 conduction, we notice that the Gwide copied 

 our extract from Cheshire upon " Chaff ver- 

 sus Dead (?) Air." Following it is a short 

 editorial from which we extract the follow- 

 ing : " We think there would not be so great 

 a difference manifested if the walls had been 

 lined with waxed paper ; it is the pores 

 through the wood that caused the circulation 

 and escape of the heat. With a good job 

 with our air tight chambers between the 

 walls we still think there would be good re- 

 sults obtained." That an outer and an inner 

 wall, enclosing au air space, is vastly super- 

 ior to a single wall, as a protection against 

 cold, no one disputes ; but it cannot begin 



