i-:>riMATio.\ OF :mixeral coxsTiTL-j-:.\rs. ,s:3 



Til <'-;timate alkalies, another portion of milk is ignited, as 

 Ixfore, and the total ash dissolved in dilut(,' h\'drocliloric acid 

 and hoiled ; a few drops of barium chloride solution are added 

 containing not more than O-f gramme of barium to lOU iriammes 

 of milk, and the boiling continued for some minutes. After 

 some hours the pi-ecipitate of barium sulphate is filtered off, 

 ignitccl, and weighed ; its weight multiplied by 0-34335 will give 

 the sulphui-ic anhydride in the milk. If an excess of barium 

 fhloride has been added, a little phosphoric acid, or ammonium 

 phosphate, may now be dropped into the filtiate, though it is 

 not necessary if the quantity of barium chloride given above has 

 l>een employed. A quantity of ferric chloride solution sufficient 

 to colour the solution brown is added, and the filtrate made 

 alkaline with ammonia. The precipitate is well washed, and 

 the filtrate <'vapornt,ed and very eautiously ij^nited ; the weight 

 will give the alkaline chlorides. The residue is disscilveil in 

 wale]', and the solution should be quite clear; if it is not so, 

 a little ammonium carbonate is added, the liquid evapoiated to 

 dryness, and the residue cautiously ignited ; the i-esidue is again 

 taken up with water, the solution filtered and evapornted, and 

 the residue eautiously ignited and weii;he(l. 



The chlorine in this may In- titiated liy standard silver niti'ate, 

 iisin;.i potassium chroniate as indicator. The |)otassium and 

 siidiuni are calculated by the following formula : — 



Let W = weigfil of .itfialine cliloriifis 

 and C = weif,'fi( of cliloriiio tlicieiii. 



Tlic woiglit of indium -. ■2'.Kn ( ' 1 ■-12.")4 W. 



,, potassium = 2-4i")4 W - 3!l!)7 ( '. 



The potassium may bc^ directly estimated by evaporating the 

 solution of alkaline chlorides with an excess of platinum tetra- 

 chloride solution almost to dryjiess : the pasty residue is treated 

 with 80 per cent, alcohol containing al)out •") per cent, of ether, 

 and washed repeatedly with this ; the alcohol is ])assi'd through 

 a weighed filter or, preferably, a Gooch crucible, and the preci- 

 pitate is finally transferred to this and washed with ether. It is 

 then dried at HM)- C. and weighed; the weight multiplied by 

 0-.3(i5(i will give the potassium cldoride : this subtracted from the 

 weight of the alkaline chlorides will give the sodium chloride. 



The potassium chloride multiplied by t)5i44 will give potassiimi 

 and by 0()314 potash. The sodium chloride multiplied by n-3032 

 will give sodium and by Oo"2i)0 soda. 



The above seheme of analysis has been worked out so as to 

 use as little milk as possible, as the amount available is some- 

 times limited. .Many obvious modificatious are available and 

 will rcadilv suijwst themselves to aualvsts: thus the chlorine 



