Fire-places and Kitchen Utensils. 341 



as to render it perfectly insoluble, and consequently 

 perfectly inert and harmless; but still the fact ought 

 to be well ascertained before it is admitted. 



A large proportion of the calx of lead enters into 

 the composition of flint glass, yet it is not probable 

 that flint glass ever communicates any thing poisonous 

 to food or drink that is kept in it. But, on the other 

 hand, there is reason to conclude that the glazing of 

 common pottery, which is likewise composed in part 

 of calx of lead, is not equally safe, when earthen ves- 

 sels covered with it are used as implements of cookery. 

 In some countries the use of such vessels in the pro- 

 cesses of boiling and stewing is forbidden by the laws, 

 under severe penalties; and in this country it is not 

 customary to use earthen vessels, so glazed, for preserv- 

 ing pickles, and other substances designed for the use 

 of the table which contain strong acids. 



The best glazing for earthen vessels that are to be 

 used in preparing or preserving food is most undoubt- 

 edly made with common salt, as this glazing (which 

 appears to be merely the beginning of a vitrification of 

 the earth at the surface of the vessel) is not only very 

 hard and durable, but it is also perfectly insoluble in 

 all the acids and other substances in common use in 

 kitchens, and contains nothing poisonous or unwhole- 

 some. 



A large proportion of lead enters into the composi- 

 tion of pewter ; but it has lately been proved, by many 

 ingenious experiments made to ascertain the fact, that 

 the lead, united to tin and the other metallic substances 

 that are used in composing pewter, is incomparably less 

 liable to be dissolved by acids, and consequently much 

 less unwholesome than when it is pure or unmixed with 



