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of attacking glass, so that fluor-spar is used in making a kind of 

 ink for writing on glass. By dissolving chalk or marble in 

 hydrochloric acid and evaporating the solution we obtain calcium 

 chloride, a substance not to be confounded, as I have already said, 

 with chloride of lime. To the chemist, at any rate, this substance 

 is of great use on account of its great attraction for water. This 

 property renders it suitable for drying gases and removing 

 moisture from the many organic chemicals which have hitherto 

 been made mainly or exclusively in Germany, but which we hope 

 will in future be produced at home. The crystallised chloride, 

 mixed with snow, forms an excellent freezing mixture, having a 

 much lower temperature than is reached by a mixture of salt and 

 snow. By mixing a solution of it with a solution of carbonate of 

 soda we get the precipitated chalk, to which reference has already 

 been made. In the first lecture of the series I spoke of calcium 

 sulphide as being used in making luminous paint, match-boxes 

 and the like. 



I have now mentioned about thirty-three uses or sets of uses 

 of lime and its derivatives. There are doubtless many others 

 which I have not thought of, and probably still more of which I 

 have never heard. Still I think that those I have described are 

 quite enough to justify the claim of calcium to rank among those 

 chemical elements whose compounds have a wide and varied field 

 of usefulness. 



