i 4 4 



Progress in Science. 



[January j 



pressure steam on the same substance. The apparatus employed is shown in 

 the engraving, a a is a bronze autoclave, made in one piece, and of great 

 strength. Before being employed it was tested by means of a hydraulic 

 pump° and was found to withstand a pressure of 500 lbs. to the inch without 

 leakage. Before using the instrument a ring of vulcanised india-rubber was 

 placed between the autoclave and its cover, b b. The screw, c, which serves 

 to keep down the cover, is forced home by means of a wrench applied at l. 

 The arms, d d, serving to support the screw, are affixed to projections on the 

 autoclave, by movable steel pins inserted at e e. A screw-tap, F, enables the 

 product to be distilled over at the conclusion of the operation. The pressures 



Fig. 3. 



are indicated by the gauge, g. A 

 cylinder of perforated metal, H, is used 

 to contain the substance to be experi- 

 mented upon ; which, in this case, was 

 pine sawdust. The shelf, 1, also per- 

 forated, prevents contact of the saw- 

 dust with the water, the level of the 

 latter being shown at K K. The water 

 and the charge of sawdust having been 

 introduced, the apparatus was immersed 

 to about half its depth in an oil-bath, 

 the temperature being carefully regu- 

 lated by means of a thermometer. The 

 oil-bath was then heated until the gauge 

 indicated a pressure of 100 lbs. to the 

 inch ; this pressure was maintained in 

 some experiments for three, and in 

 others for four hours, the average tem- 

 perature of the oil -bath being about 

 198 C. The apparatus having been 

 allowed to cool until the pressure had 

 completely gone down, was then con- 

 nected with a condensing arrangement. 

 The screw, f, was then loosened, and 

 heat was applied to the oil-bath until 

 about three-fourths of the water pre- 

 sent had distilled over. The distillate 

 was strongly acid to test-paper, and 

 smelt decidedly of furfurol, mixed with 

 an empyreumatic odour. On the addi- 

 tion of ammonia it acquired a yellow tint, and in a few hours deposited 

 the characteristic crystals of furfuramide. The crude distillate, mixed 

 with aniline and acetic or hydrochloric acid, instantly gave the magnifi- 

 cent crimson colouration indicative of furfurol. To prove that the crystal- 

 line precipitate with ammonia was really furfuramide, this was distilled 

 with a very small quantity of hydrochloric acid; the distillate immediately 

 gave the crimson reaction with aniline. The crystals, treated with acetic 

 acid and aniline, also readied in the same manner. The author next 

 proceeded to ascertain whether wood would yield furfurol when distilled 

 with water at normal pressures. He therefore distilled roo lbs. of sawdust 

 with 100 gallons of water, in a still heated by a copper steam coil : 20 gallons 

 were distilled over. These 20 gallons were put into a small copper still, and 

 the first 10 gallons received. These in their turn were rectified again, and 

 two received. In spite of the concentration which these liquors had under- 

 gone, furfuramide was obtained on digestion with ammonia, and, in fact, they 

 only contained minute traces of furfurol. 



