5(30 APPENDIX. 



bv fusin" tho ends of both in the same flame. As soon as the joining 

 Died sli-htly. the- tube to be closed is heated again at a short dis- 

 tance from its end. and drawn out as before 



.After glass has been strongly heated it must be allowed 

 radually as possible, in order to anneal it. 



.; r,,,-/.-x. To fit properly, a cork must be somewhat 

 larirer than the opening it is intended to till. Before pushing it in, it 

 Should always he reducrd by compression, either with a cork-squeezer 

 or in its absence, hy rollinir it on the floor (protected by a covering ot 

 paper) under tin- tout. For shaping corks, a shoemaker's knife which 

 ha* I'een -harpened on a rounh stone answers best. Any knife with a 

 .ill do. To perforate a cork, a piece of brass tubing, the 

 ; one mil of which is sharpened, is used. It is best to work the 

 borer trom tin- opposite ends, the two bore-holes meeting in the middle. 

 A- the holes always require finishing with a rat's tail file, a borer 

 smaller than the intended channel should be used. 



207. Solution and Ebullition. The different solubility of various 

 organic substance- in regents, such as water, ether, alcohol, acids, 

 alkalies, and saline solutions, not only sen es as a means of separating 

 them from each oilier, but in many instances, MS in the case of albumi- 



Doas bodies, furnishes a characteriatic by which one substance maybe 



distinguished from others nearly allied to it. Tests are also more gene- 

 rally and conveniently applied to solutions than to bodies themselves. 



Solution takes place more readily when the body to be dissolved is finely 

 divided. Drvand hard substances are therefore generally pulveri/ed by 

 poundini: and rubbing in a Wedgewood mortar. If too large to be con- 

 venientlv triturated at once, they may be previously broken in an iron 

 mortar, or by wrapping them loosely in brown paper and pounding 

 tin-in with a hammer. If the substance is constantly shaken or stirred 

 about so as to bring it continually into contact with fresh portions of the 

 solvent, it will dissolve much more quickly than if allowed to remain 



/"/ prfimrinri friliitinH*. \ beaker is for most purposes the most 

 convenient vessel, a* its contents can be stirred at the same time that it 

 i- subjected to heat, which always accelerates solution. To avoid risk 

 of fracture, the beaker must not be heated over a naked flame, but must 

 lie placed (in a piece of wire gau/.e or sand bath i fig. JV28), supported on 

 a tripod. Flasks may be employed instead of beakers for solution or 

 boiling when stirring' is not required. They have the; advantage of 

 i' fluid during the process of ebullition, as any particles 

 which spurt up are caught against the sides of the flask, especially if 

 it is placed in an inclined position, instead of falling outside as in a 

 beaker. 



To i /(ion. Various methods may be used. One 



of these consi>!s in placing a small funnel in the mouth of the flask ; 



the fluid condenser, in the funnel and runs hack into the flask. Another 



method is to close the neck of the flask with a cork, through which a 



wide glass tube, drawn out to a capillary opening at its upper end, is 



i. A considerable part of the vapor passing from the boiling liquid 



tensed in the tube and falls back into the flask. If the boiling 



is long continued, the tube L r ets very hot and a great, deal of vapor 



Bo avoid this, the escape tube is prolonged and surrounded 



hv a I.irlii-'s condenser, for which purpose it must be bent at an angle 



oi about I'Jli . as Men in fig. --".I. 



To exhaust a substance with ether, the ether and the substance should 

 be placed in one tlask, with which a second is connected by a bent glass 

 tube which passes through the cork of both. The tube, which scarcely 

 projects beyond the under surface of the cork in the first flask, reaches 



