g EDWARD DIVERS. 



Quartz 38.4 



Combined silica '24.2 



Alumina 2(5.3 



Ferrie oxide 10.5 



Magnesia 0.2 



The magnesia is only got by fusion of the finely ground earth 

 with alkaJi carbonate, and belongs to the particles of mica scattered, 

 through it. Only doubtful traces of plios])horic acid could be found 

 and, what is specially to be noted, no hnie wli;itever. The earth is 

 thus nothing but (|uartz, kaolin, ferric hydroxide, and a ver}'^ little 

 biotite, and is probably valuable to the calomel maker not only for its 

 highly porous texture, l)ut also for its negative chemical qualities. 



The bittern and even the rough bay-salt ccmtain magnesium 

 chloride, and this rather than sodium chloride must be the source of 

 hydrochloric acid in the process. That air finds a graduated entrance 

 to the other materials by diffusion during the jjrocess, will become 

 evident from a consideration of the set-up of the a])paratus. 



(.'/" the plant. — The apparatus for making 'bipanese calomel con- 

 sists of a tal)]e-fiu-nace supporting sixty cast-iron ]jots lined and sur- 

 mounted with the Shunakayama e;irth, on which rest, as covers, and 

 condensers and receivers of the calomel, unglazed chiy cups bottom 

 upwards. In PI. I. the furnace as it is when in action is seen from 

 the working side ; ten ])ots on the left side are shown still to be 

 charged and co\ered. The wooden step in front is to enable the 

 workman tu reach over the table easily when charging the pots or 

 em|)tying them. In PI. II, fig. 1 the furnace is seen from the back, or 

 firing side, and with the walls broken away to show its interior and the 

 method of firing. In 1^1. II, tig. 2 the mounting of the pots is shoAvn 

 in three stau'es bv sectional i)lans (jf the table. 



