/77 



SynthesU of Swjar 77] . 



.the neutral ionnate pres-jiit was not realised, and hence further 

 estimations were carried out in tiie same manner eh for calcium. 



It is, however, difficult to ohtain exact quantitative deternrna- 

 tions owing to the delay in the completion of the reaction after 

 each addition of soda. If the latter is added too rapidly, so that 

 any precipitate forms, this only dissolves very 'slowly, and any un- 

 <.dissolved precipitate represents so much neutralised caustic 8oda. 

 If, however, tlie ])oiling is very proloncjed, the li(iuid turns yellow, 

 while still containing fornialdeliyde, and when the reaction is com- 

 pleted the liquid appears to contain more hy-prcducts other than 

 sugar. At least the liquid from a reaction completed in two hours 

 boiling contained from 5 to 10% more reducing sugar, as deter- 

 mined by the Pavy method, than one completed by six hours' boil- 

 ing, and the latter required slightly less caustic soda, although nil 

 other conditions and quantities were the same. 



For these tests it was found best to use a simple type of con- 

 densing flask, with tlie burette passing through the cork, and with 

 an open upright tube 4 ft. long as the condensing column. Of the 

 ^00 c.c. of water used 100 c.c. was allowed to trickle slowly down 

 this tube during the two-hour period over which the l)<)iling, and 

 addition of soda, were spread when strontium and barium salts 

 •were used. As the soda burette becomes slightly warmed during the 

 boiling, its final reading must be checked after it has cooled to 

 the original temperature. 



Strontium. — Cry i^t&Wised strontium formate was used as a 10% 

 solution. Tlie proportions used were 20 c.c. of strontium formate, 

 500 c.c. water, and 70 c.c. of 31.5 formaldehyde. The amoujits 

 of 3.5% sodium hydrate required varied from 20.8 c.c. to 21.2, 

 representing an apparent polymerisation of formaldehyde of 65%. 



Bariicm. — In the presence of barium formate, using similar 

 quantities, the reaction was slighly more rapid. The amounts of 

 «oda required to neutralise all the formaldehyde varied from 20.4 

 to 20.9, representing a percentage polvmeriRati..n of formaldehyde 



of 65 to 66%. 



Magnesium. — Osviug to the highly insoluble character of tho 

 hydrate, its polymerising action is extremely slow, and quantita- 

 tive estimations are difficult to obtain. A j.reliminary estimation 

 Avas made, using an excess of tho hydrate precipitated in the liquid 

 bv caustic soda. In this case the only advantage of using caustic 

 soda is that the hvdrate is pre<ipitated in a more bulky and 

 flocculent form than if the dry hydrate is ummI. Krom the an.ount 



