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biology. We may first consider how the experiments are 

 carried out. Next, what are the results obtained ? Then 

 we may consider any possible or probable way of accounting 

 for them, and finally, any possible connection with natural 



Method of Conducting Experiments.— A solution of 

 ordinary water glass, such as is sold for preserving eggs, 

 is taken and diluted with water to a known density. I 

 generally use a Twaddell's hydrometer to test density, and 

 have tried solutions from 4° to 26° Tw., that is, from 1'02 

 to 1*13 sp. gravity. I find if the solution is very weak 

 the growth is slow or does not take place at all, while if 

 very strong it does not usually go on well. A solution of 

 about 16° Tw., 1*08 sp. grav., is found to be the most 

 generally useful strength, and although some salts may 

 grow better in rather weaker solutions and others in 

 stronger, yet I have thought it better to keep, in the main, 

 to one strength, and most of the experiments hereafter 

 described, have been carried out with the 1C° solution. 



Having obtained our solution and* placed it in a test tube 

 or other similar vessel, we drop in a crystal or crystals of 

 the salt we desire to experiment with and await results. 

 After a time, it may be a few minutes, as in the case of 

 aluminic chloride, it may be nearly a week, but usually in 

 the course of an hour or two, growth begins and goes on 

 for some time and then stops. Usually salts which begin 

 quickly soon attain their full growth, while those which 

 begin slowly may take a week or more and still show signs 

 of change. The solution usually remains quite clear, and 

 although coloured salts give coloured growths, the colour 

 rarely passes into the solution. If, however, strong hydro- 

 cloric acid be added to the solution a notable change occurs. 

 The base of the salt appears to go into solution, which 

 becomes coloured, while the growths usually retain their 



