tarr] some COMMOX MIXERALS ' 323 



gested in the column headed ''Remarks." Where the minerals 

 are very hard to distinguish, attention has been called to this 

 fact and the best methods for telling them apart are suggested. 



These notes correspond to the numbers in the table that follows : (1) This min- 

 eral is the result of the decomposition of minerals that contain aluminium, such as the 

 feldspars of the granites, gneisses, etc. Where the decomposition has been extensive 

 the beds of kaolin are very thick. The name comes from the Chinese word Kauling, 

 which means high-ridge, and is the name of a hill in China where the material is 

 obtained. 



(2). Isinglass is a common name for mica but true isinglass is a nearly pure 

 gelatin obtained from certain parts of such fish as sturgeon and cod. Both the 

 micas are found in granites and other igneous rocks. 



(3). Crystals of salt can be readily made in the schoolroom by allowing a 

 concentrated solution of salt water to slowly evaporate. If a string is suspended 

 in the solution, the crystals will attach themselves to it. They occur in the form 

 of cubes, very often with concave sides. 



(4). Calcite is one of the commonest minerals known. It occurs in a great 

 many crystal forms. Some of these are shown in the plate of figures. Limestone 

 and marble consist largely of small calcite crystals. The varieties of this mineral 

 are too numerous to mention here. The uses of calcite are almost as numerous. 

 Besides its use in building operations, it has the following chemical uses : As a 

 fertilizer; as a bleaching agent for cloth and rags, etc.; in the manufacture of soda, 

 potash, and ammonia ; m making wood alcohol ; in refining mercury ; in purifying 

 coal gas ; in the manufacture of glass and glazes ; in making rubber, glue, dyeing 

 fabrics, as a polishing material ; in the manufacture of oils and soap ; in making 

 paints and varnish; in making papier : in preserving eggs; as a disinfectant and 

 purifier of water and sewerage ; in smelting the various ores ; in sugar manufacture ; 

 in the tanning industry ; and softening water. 



(5). Hornblende is generally darker than pyroxene, occurs in long slender 

 crystals, which are six-sided (see figure 10), and may be fibrous. Either the 

 crystal or cleavage faces will give the characteristic outline that is shown in 

 figure 12. Augite appears in section as_ in figure 11. The cross lines in both 

 figures indicate the cleavage. It is best in hornblende. 



See advertisement of minerals. Ward's Natural History Establishment, P. 344. 



