152 On the substitution of Tubes for Bottles. [1825 



unperceived way into the experiments, they will still show the 

 extreme delicacy of heat, or heat and potash, as a test of its 

 presence by the formation of ammonia. 



With respect to the delicacy of the test, it may be observed 

 that it offers many facilities to the detection of nitrogen when in 

 certain states of combination, which chemists probably were 

 not before aware of. A portion of asbestos, which had been 

 heated red-hot, was introduced into a tube by metallic forceps 

 and heated ; it gave no ammonia ; another similar portion, com- 

 pressed together, and introduced by the fingers, gave ammonia 

 when heated. A very minute particle of nitre was dropped 

 into hydrate of potassa, and heated to dull redness ; it gave no 

 ammonia ; a small piece of zinc-foil, dropped in and the heat 

 applied, caused an abundant evolution of that substance. 



The circumstance also of absorption by lime and other bodies, 

 of something from inhabited atmospheres, which yields am- 

 monia when thus tested, is very interesting ; and Dr. Paris has 

 suggested to me that this power may probably be applicable to 

 the examination of the atmosphere of infected and inhabited 

 places, and may perhaps furnish the means of investigating 

 such atmospheres upon correct principles. 



February 17, 



On the Substitution of Tubes for Bottles, in the preservation 

 of certain Fluids, such as Chloride of Sulphur, Protochlo* 

 rides of Phosphorus and Carbon, $c* 



THERE are many fluids in the laboratory which are much more 

 conveniently retained in tubes, such as that depicted, fig. 5, 

 plate I, than in bottles, and from which they may be taken in 

 a less wasteful manner when required for the purpose of expe- 

 riment. A piece of glass tube, a quarter of an inch or more in 

 diameter, being selected, is to be closed at one end by the 

 blowpipe ; and then, being softened near the other end, is to 

 be drawn out obliquely, so as to form the long narrow neck 

 represented in the figure, but to which, in the first case, 

 the short piece of tube is to be left attached ; this forms a 

 funnel, into which the preparation to be preserved is to be put. 

 Then, warming the body of the tube, the expanding air passes 

 * Quarterly Journal of Science, xix. 149. 



