POLYMERIZATION OF FORMALDEHYDE 61 



The first successful attempt to bring about such a poly- 

 merization was made by Butlerow in 1861, who, by the 

 catalytic action of lime water, at ordinary temperatures, on 

 trioxymethylene (itself a polymer of formaldehyde), obtained 

 a syrup with a somewhat bitter taste, which he called methyl- 

 enitan. Subsequently Loew undertook an investigation of 

 the action of milk of lime on formaldehyde, and devised the 

 following experiment. A 4 per cent, solution of formaldehyde 

 is mixed with an excess of milk of lime and repeatedly shaken 

 for about half an hour ; after filtering, the mixture is set aside 

 for some days until the pungent smell of formaldehyde has 

 disappeared. The solution, which will now reduce Fehling's 

 solution, yields a colourless syrup with a very sweet taste.* 

 This substance, which is known as crude formose, was exam- 

 ined by Emil Fischer, who found it to consist of a mixture of 

 various hexoses and succeeded in isolating from it a small 

 quantity of a sugar — acrose. Acrose can also be obtained by 

 the action of dilute caustic soda on glycerose, a substance 

 obtained by the oxidation of glycerol. From the acrose thus 

 formed Fischer was able by an elaborate series of reactions to 

 prepare ordinary fructose or levulose. In respect to the action 

 of weak alkalis, Spoehr found that sunlight had no action on 

 a 3 per cent, solution of formaldehyde in the presence of such 

 salts as calcium carbonate, potassium carbonate, and potas- 

 sium nitrate in decinormal concentration, no trace of sugar 

 being found after an insolation period of four months. 



With regard to the formation of the higher carbohydrates, 

 Fisher and Armstrong f were able to synthesize a disac- 

 charide — isolactose — by the action of an enzyme, Kefir lactase, 

 on a mixture of glucose and galactose ; the same authors 

 also synthesized melibiose ; similarly isomaltose has been ob- 

 tained by Croft-Hill $ by the action of maltase on glucose ; 



* More recently Ewart (" Proc. Roy. Soc," Victoria, 1919, 3'> 3 28 ) 

 has worked out the best conditions for the polymerization of formaldehyde 

 to sugar, and finds that the most rapid reaction is produced by sodium 

 hydroxide in the presence of a neutral calcium salt. 



f Fisher and Armstrong : " Ber. deut. chem. Gesells.," 1902, 35, 3144. 



t Croft-Hill : " Journ. Chem. Soc," 1898, 73, 634 ; see also Emmer- 

 ling : " Ber. deut. chem. Gesells.," 1901, 34,, 600, 2206. 



