Lesson n. 



MISTRY. 





blow-pipe, and a red-hot wire. A common tobacco-pipe makes a tolerable temporary 

 blow-pipe ; and a common flower-pot an excellent extemporaneous furnace; but these 

 we must leave for the present, to consider affinity or chemical attraction, 

 which is the basis of Chemistry. 



QUESTIONS. 



is chemical affinity ? 

 P. !t is that property of matter which 

 causes heterogeneous or dissimilar bodies 

 to combine, and form compounds fre- 

 quently quite different from the sub 



compose them. For example [Ex- 

 . I will dissolve these copper 



. or this piece of copper wire, in a 

 little sulphuric acid (oil of vitriol), and 

 allow it to crystallize, and then we shall 

 get a salt commonly called blue ttone (sul- 



f copper), which is quite different 



.e acid, or the metal in its appear- 

 ance or properties. Caustic vegetable 

 alkali will corrode the flesh, and so will 



\itriol; but when these two arc 



. we get a salt called sulphate of pot- 

 ash, which may be swallowed with safety. 



/'. Why did you call potash a 

 vegetable a 



]'. . it from so.la the 



mineral, and ammonia the volatile alkali. 



/'. It appear*, then, that change 

 of form and \< n results of chemi- 



cal c< Is it so f 



/'. - olid* will produce a fluid. 



[Experimei. a lump of solid 



ice, and a lump of salt, anotlr 

 1 place these two tope: 

 combine and form a fluid [places them in 

 contact.] You observe that we ha 

 .1 quantity of brine by our 



D of the substances 



are altered. Again, tolidt will produce a 

 gat. are a few 



grains of gunpowder, and you will see that, 

 the end of this heated wire 

 on them, tlu-y will explode, 



to a gaseous form. Two # ascom 

 bodiet will form a totid ; thus, 

 vapour of an nc acid 



gas, dense white fume* will be pr< 

 which then collect in flakes ai 

 ides and bottom of the jar; this j 

 is muriate of ammonia or sal an 



ift trill product a liquid. [ I 

 ! . J I have some oleAant gn 

 h is marked O, and an equal volume 



of chlorine gas in the jar marked C, and 

 if you observe closely you will see an oily 

 compound produced, when the two gases 



d [mixes them]. You see it col- 

 lects in large drops on the sides of the jar 

 in which they were mixed, and the gases 

 are being gradually absorbed. This oily 

 compound is called chloride of defiant gas ; 



nve other matters to consider before 

 we can describe all about the gases. 



18. T. Are there not other changes of 

 form ? 



P. Yes : but the consideration cf them 

 would occupy teo much of our time. 



[The pupil should be required to give some ex- 

 amples of those changes of form and quality, 

 x ample, a liquid and a tolid form a 

 liquid (salt mixed with wau-r). Liy. 

 dtice gate* (nitric, and hydrochloric acids, 



1!). T. Are all bodies affected in the 

 same manner .' 



P. No ; the attractive force is exerted 

 with different degrees of force }> 

 different bodies ; sometimes it acts very 

 feebly, sometimes with great ener ; 

 at other 

 at all. 



20. T. How do you know that all bodies 

 are not similarly affected ? 



MI. [Expcrim 

 Here is a piece of camphor. 



1 when it is placed in this wine- 

 glass, containing alcohol, it will ii. 

 .lie alcohi '.. 

 Now, if son 

 into the glass 



:h the 

 , 



.sition both <. :he water 7 



combines with the alcohol, a; 

 !ior and nl 



21. T. Has no! tlr ; combination been 

 called itieuUr n . 



/'. ") ' tingle 



P. Why .! 



vT 



