Infusorial Earth and its Uses. 
341 
1876.] 
Being a very poor conductor of heat, it has been sug- 
gested and applied for surrounding ice, beer and ale cellars, 
fire-proof safes, steam-boilers, powder-magazines, refrigera- 
tors, &c. The results of certain experiments lately made by 
Refardt and Co., of Braunschweig, to ascertain how this 
material compared with other substances generally employed 
for the purpose, are highly favourable to the merits of infu- 
sorial earth for this application. 
Without entering into the mechanical details of the appa- 
ratus employed in these trials, it will suffice to state that in 
the time required to melt 100 parts (by weight) of ice sur- 
rounded by the siliceous earth, 235 parts of ice were melted 
in a cylinder surrounded with an equally thick layer of dry, 
light garden earth. Moist earth, and moist materials gene- 
rally, gave still more unfavourable results. Again, for every 
100 parts of ice melted when protected by the infusorial 
earth, 142 parts of ice protected by dry, sifted coal ashes, 
were melted. The results obtained with flax-shives were 
about the same as with the infusorial earth. These trials 
demonstrated that infusorial silica and flax-shives offer the 
greatest amount of resistance to the transmission of heat ; 
that dry coal-ashes are far less efficient, and moist ashes still 
more so ; and finally that earth, as compared with these, is 
very inferior as a non-condudbor. The use of the infusorial 
earth is therefore highly recommended for filling in between 
the walls, and for covering the mason work in ice-cellars. 
For this purpose the following additional advantages are 
urged in favour of this substance, viz. : — It is extremely 
light, — being nearly five times as light as dry earth, and 
about half the weight of dry coal ashes, — and it is not com- 
bustible, remaining unaffedbed in the hottest fire. These 
properties, to quote from the published account of the above 
trials, render this substance preferable to flax-shives, tan- 
bark, peat, saw-dust, and similar materials, which are about 
equal to it in non-condudbing quality, but which are com- 
bustible, and when kept for some time rot or moulder, shrink 
and settle, and might under some circumstances, take fire 
spontaneously (sic/). 
The infusorial earth, it is further claimed, will be found 
highly useful in fire-proof safes, as a surrounding for powder- 
magazines on shipboard, for covering steam-pipes and 
boilers, and for all similar purposes. Reference is made in 
some of the encyclopaedias (vide “American Encyclopaedia,” 
iii., 268) to what are termed floating bricks, which, according 
to account, are made of infusorial earth, and are named in 
virtue or their power of floating upon water. Clay is some- 
