r>SS I'KINCII'LKS OF CIIK.MISTKY 



ceptible quantity of magnesium hydroxide namely, one part is dis- 

 solved by ."), r )000 parts of water. Such a solution. however, has 

 an alkaline reaction, and gives, with a salt of phosphoric. 1 acid, a 

 precipitate of magnesium phosphate, which is still more insoluble. 

 Magnesia is not only dissolved bv acids, forming salts, but it also dis- 

 places certain other bases for example, ammonia from ammonium 

 salts when boiled: and the hvdroxide also attracts carbonic anhy- 

 dride from the air. The magnesium salts, like those ofcalcium, potas- 

 sium, and sodium, are colourless if the\- are formed from colourless 

 acids. 'I hove \\ liich are soluble have a bitter taste, whence magnesia 

 ha- been termed li'ttfi-r-i-nrth. In comparison to the alkalis magnesia 

 is a feeble base, inasmuch as it form- somewhat tin-table salts, easily 

 U'ives basic salts, forms acid salts with ditliculty. and is able to give 

 doulile Milts with the salt- of the alkali--, which facts are proper to 

 t'-cble bases, as we shall see in becoming acquainted with the ditlerent 

 metals. 



The power of magnesium salts to form double and basic salts is 

 \ "i-y frequently shown in reactions, and is speciallv marked as re- 

 gards ammonium salts. If saturated solutions of magnesium and 

 ammonium -ulphates are mixed together, then a crvstalline double 

 -alt. .Mgi X 1 1 ,) ,(S< ), ).,,fi| I O,-" I. immediately precipitated. A strong 

 solution of ordinary ammonium carbonate dissolves magnesium 

 o\idc or carbonate, and precipitates crystals of a double salt, 

 M'j' N I T, ),(('<).,).,,! 1 1 .,< ). from which water extracts the ammonium 

 carbonate. \Vith an excess of an ammonium salt the double salt passes 

 into solution.- 1 and therefore if a solution contain a magnesium salt 

 and an excess of an ammonium salt for instance, sal-ammoniac 

 then sodium carbonate \\ill no longer precipit at e magnesium carbonate. 

 A mixture .if ,-olutions of magnesium and ammonium chlorides, on 

 evaporation or refrigeration, gives a double salt, M L;( N 1 1 , )( 'I.,,!! II ._,<>.-- 



K\cn -i -.ilntini] ni' ;iiiiin(iiiiiiiii 

 It- P. . !'. I - 7 - J : lint ji;ir1 ':..'' 



\1 I.Miit 1:;n it I..-,. ti-r. 



" Tin iimj.lf .!' i'(iiiilil.i'iii]ii nii.l ..I tli.' intliicncr i.f mas- ; the .IniiliU- vjilt is 



ili-i'i,|ii|.i.-fil liy \\.itcr.liiit ,1 we tiiki' .! .. ' n] llial |>,irt \\lii.li is l'ni'iiic.1 in thtj 



t. .1 , all. 



It jin ex.'.... ,,[' ainnK.iii.i In' ail.li-il t,, a M.liifi..n r.f ma : ji].-iu in clilnriilf, tlirn only 



'!,. iiia'jnc-iuni i- --|iarat'il in tin- | >\ v,-i | ,il .. t .-. -1 M -( '] , ~1 \ 1 1 ,.( > 1 1 M : _" < )H K - 



\|_ NH.C] N'If,( ' A nhiVinii ( ,f aiiiinoiiluiii rliluri.I.- reacts with niau'iH-ia. <'V<>!vin 



. MHI'.IM!) an<l f-.nnii;- a m.luJ if m of t li- -am.' .ill. M j< ) :'A 1 1 ,( '1 M _ N 1 1 ,< M- I \.,< > 



"'. I ! 



,.,1,,iil,l,.- i i1f^ t ,| iiiiiiiK.iiiuiiiiiinliiM^iii^i tin- j.lio^i.lial.-.M-N I !,!'() ; .r,IIoO, 



nnia. Ma'_ r iif-ia i- vcr\ f i '<) n'iii 1 \ ]>n-f\ pit .1 1 .-i 1 a- this -alt i'min -(ilutions in which 

 held hi, ainiiiMiiiiiin -alt^. As lin 



