The Story-Book of the Fields 



others, become harmless and even form part 

 of our food. This is the case with phosphorus. 

 We will try to discover what it is that is 

 combined with phosphorus, so that it is no 

 longer poisonous and forms part of our meat 

 and flour. 



When phosphorus is burnt a thick white 

 smoke is produced, as you may see by burning 

 a few matches. This white smoke, under the 

 influence of the least damp, turns into a 

 liquid with an extremely sharp taste, which 

 is called phosphoric acid. Since this sub- 

 stance results from the combustion of the 

 phosphorus, in the same way as carbonic 

 acid gas does from the combustion of carbon, 

 it ought to contain, and does contain, the 

 air that is required by all burning matter. 

 This phosphoric acid is no longer inflammable, 

 however much it is heated ; for, being itself 

 the result of combustion, it cannot be burnt 

 again. But although there is no risk of 

 burning by phosphoric acid, it is neverthe- 

 less dangerous on account of its extreme 

 sharpness, by which it easily eats away flesh. 

 This formidable substance, when associated 

 with lime, loses all its noxious qualities and 

 becomes white and perfectly tasteless, losing 

 its poison altogether. It is then called 



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