Combustible Substances. 203 



cined, till they cease to smoke or to give out any 

 odour, and let them afterwards be reduced to a 

 fine powder. Put one hundred parts of this 

 powder into a stoneware bason, and add gradu- 

 ally (stirring the mixture) forty parts of sul- 

 phuric acid. Leave the mixture for twenty-four 

 hours, stirring it occasionally. Strain the liquid 

 into a porcelain bason through a filter of cloth ; 

 the white powder which remains may be thrown 

 away. After this, pour slowly into the liquid 

 acetat of lead dissolved in water, when a white 

 powder will be precipitated. This white pow- 

 der, after being washed, is to be mixed with one- 

 sixth of its weight of charcoal powder. It is then 

 put into a retort, which is placed in a sand bath, 

 and the beak of it plunged in a vessel of water, 

 and after some time the phosphorus will come 

 over and congeal under the water. I have phos- 

 phorus now in my possession twenty years old, 

 which retains all its properties. It has of course 

 been kept in water. 



Phosphorus combines with sulphur in different 

 proportions: when the phosphorus exceeds, it 

 is called phosphuret of sulphur ; when the sulphur 

 predominates, sulphuret of phosphorus. When 

 used internally it is a poison. 



The combinations of the phosphoric acid with 

 different substances, or phosphats, are very nu- 

 merous. Phosphate of lime is the basis of all 

 bones, whether human or of other animals, and 

 this is the reason of the above process, which ex- 



