APPARATUS FOR ILLUMINATION. 171 



gether with cleanliness and cheapness combined. May not 

 such a liquid be found among the products from the distillation 

 of coal, to be used either by itself or in conjunction with 

 other substances ? 



3. Apparatus for Illumination. — We have nothing novel to 

 present in relation to lamps and jets, except a remark upon 

 reflectors. 



Reflectors are found to increase the ordinary efiect of a 

 light in proportion to the perfection of their reflecting surface 

 and their approach 4o a parabolic form ; but, being constructed 

 of metal, they are expensive. Kempton (Lond. Journ. 1849, 

 330) proposes making earthenware reflectors of a good form, 

 and then lustring their reflecting surface in the usual manner. 

 Clay-ware is undoubtedly an excellent material for giving a 

 good form to a reflector, as it is readily and cheaply made, and 

 retains its shape tolerably well during burning. But the new 

 method of precipitating silver from solution, with a brilliant 

 surface, might advantageously be substituted for the method 

 usually adopted for lustring pottery with silver. 



