186 ANNUAL OF SCIENTIFIC DISCOVERY 



MELSENS'S PROCESS FOR THE MANUFACTURE OF SUGAR. 



THE French Minister of Agriculture, during the early part of the 

 past year, despatched M. Guiet to the French Colonies, to observe 

 and experiment upon the celebrated process proposed by M. Melsens 

 for the manufacture of sugar. The first report is dated at Guadaloupe, 

 20 April, a synopsis of v, inch is given in the London Patent Journal. 

 Up to the period indicated, M. Guiet had made but few experiments, 

 and those not under favorable circumstances; the results, however, 

 were such as to lead to the expectation that the bisulphite of lime will 

 be advantageously employed in the Colonies in the manufacture of 

 sugar. According to the first observations, the cane-juice, preserved 

 from fermentation by means of the bisulphite of lime, can be made to 

 undergo, without inconvenience, a decantation and filtration before 

 being cleansed or defecated. The bisulphite of lime will also arrest 

 the fermentation of the canes, which are oftentimes left, after having 

 been cut, exposed to the heat of the sun, when any interruption takes 

 place in the pressing process. M. Guiet appears to think that the 

 ingenious process of M. Boucherie* for the preservation of wood may 

 be applied to the injection of any of the sugar-cane with the bisulphite 

 of lime, thus preserving it from fermentation. He has commenced a 

 series of experiments on this subject. 



SCOFFERN'S IMPROVEMENTS IN THE REFINING OF SUGAR. 



No subject has been discussed at greater length in the foreign sci- 

 entific journals, during the past year, than the improvements of Dr. 

 Scoffern in the refining of sugar. The chief points in these improve- 

 ments may be briefly stated. It is well known that acetate of lead 

 has long been recommended for use in preparing sugar for the boiler, 

 on account of its strong affinity for acids ; but there was this objection 

 to its application, that the refiner could never be certain that he had in 

 the end wlrolly freed the refined sugar from the lead, together with 

 the other impurities. The object of Dr. Scoffern was to attain this 

 most desirable end. He used the sub-acetate of lead, which removed 

 the coloring matter and the acids, leaving behind a small quantity of 

 lead disseminated throughout the syrup. To effect the removal of 

 this, he passed a current of sulphurous acid gas through the syrup, 

 which threw down the lead in an insoluble state, as sulphite of lead. 

 Upon the insolubility of this substance the perfection of the process 

 depends. The remaining portion of the sulphurous acid is then expel- 

 led by heat. The sulphurous acid is obtained by passing a current of 

 air over burning sulphur. The alleged objections to the process are, 

 that it is impossible to wholly free the sugar and the remaining syrup 

 from the presence of lead by the action of the sulphurous acid and the 

 subsequent crystallizations, and it is upon this point that the applica- 

 bility of the invention rests. 



* Described in this volume under Mechanics. 



