350 Chemical. Contributions. 
through its bottom, and a test tube of a suitable size luted in with 
clay. The phosphorus is put into the test tube; the top of which 
is loosely covered with a piece of broken crucible to prevent the 
small pieces of quicklime from running down into it.* The lime is 
then put in so as to fill this crucible and partly fill the upper smaller 
one, which serves as a cover to it, and is luted on with some fine clay 
a little moistened, (fig. 6.) The cover has also a small hole in its 
top to afford an outlet for the air or volatilized phosphorus if there 
should be any occasion for it. The whole is now placed upon the 
grate of a furnace, with the test tube projecting through and appearing _ 
below, and a charcoal fire kindled around it. The phosphorus may 
be kept cool if it should be thought necessary, by making the tube 
dip into the water, contained in a tin cup attached to the end of a 
stick. When the crucibles and their contents are thoroughly red 
hot, a chafing dish is substituted for the tin cup, and the phosphorus 
rising in vapor produces the desired change. The phosphuret should 
be preserved in a sealed vial. The same crucibles may be used @ 
number of times. oper kes 
__. The only purpose for which phosphuretted hydrogen is prepared 
_ is for the exhibition of its property of spontaneous combustion. A 
pleasing mode of exhibiting this is to immerse wholly the retort or 
gas bottle in which it is generated in the water of the pneumatic cis- 
tern. The gas rising at a distance from any object from which it may 
be supposed to have been derived, and taking fire at the surface of 
the water, presents a miniature representation of what the appearance 
may have been when the Azores or Sandwich Islands were about to 
émerge from the bottom of the ocean. ; 
It is the business of the chemist to ascertain the proper method of 
preparing this gas ; its composition ; upon what its extreme combus- 
tibility depends, etc. Will some one of the mathematical correspond- 
nts of the Journal, investigate the nature of the forces exerted during 
its combustion, and show how they result in the production of the 
beautiful coronet which succeeds ; and why a rotatory motion 
the axis of the coronet is impressed upon the filaments of watery 
vapor, and phosphoric acid of which it is composed ? 
Ne. at Céeho muicklime 
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th a piece of chalk. 
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