212 THE POULTRY- BOOK. 



of the shell makes it appear whether or not there be any 

 vacancy in the upper portion, as well as whether the yolk and 

 white are mingled and muddy, by the rotting and bursting of 

 their enveloping membranes. 



The transpiration of eggs, besides, is proportional to the 

 temperature in which they may be placed, cold retarding and 

 heat promoting the process ; and hence, by keeping fresh-laid 

 eggs in a cool cellar, or, better still, in an ice-house, they will 

 transpire less, and be preserved for a longer period sound, than 

 if they are kept in a warm place, or exposed to the sun's light, 

 which has also a great effect in promoting the exhalation of 

 moisture. As, therefore, fermentation and putridity can only 

 take place by communication with the air at a moderate tem- 

 perature, some means must be devised to exclude such connec- 

 tion, by closing the pores of the shell. 



The first material which M. Reaumur tried was spirit of 

 wine varnish, made with lac, and he says that " it was impos- 

 sible to distinguish the varnished eggs, which had been kept 

 for a year, from those newly laid." (L'Art de faire eclorre, 

 sub fin.) 



It is an indispensable condition of the material used for stop- 

 ping the pores of the shell of the egg, that it should not be 

 capable of being dissolved by the moisture transpired from the 

 interior, and the varnish fulfilled this condition ; but, unfortu- 

 nately, though varnish is not very expensive, it is not a com- 

 mon article in country places, where eggs are most abundantly 

 produced, while many people, besides, are not easily brought 

 to make use of anything to which they have not been accus- 

 tomed. 



In order to get over this difficulty, M. Reaumur was led to 

 try other substances, and soon found that another material, 

 very cheap and everywhere to be had, would very well supply 

 the place of varnish. This material was fat or grease, such as 



