372 PROCEEDINGS OF, THE SCIENTIFIC ASSOCIATOIN. 
the liquid to be evaporated come in contact with, many hun- 
dred feet of evaporating surface. A blast of air along this 
surface as proposed by the inventor, but not put in execution 
by him, would, if heated or even dry, have more than doubled 
the evaporative effect. Dmitri Davidou then proceeds to 
state the results obtained in the following language : “ Les 
produits bruts que j’ai obtenus Tannee passee (1836) de la 
betterave tres alteree, a l’aide de mon plan incline (apres 
lequel j’achevai la concentration du sirop dans un cylindre 
tournant) avaient la blancheur de la neige et offraient l’aspect 
du sucre en pains par le rapprochement compacte de leurs 
crystaux, mais comme les sirops n’avaient point subi Taction 
violente du feu, la saveur, etc.” 
These results are brilliant, and it is not astonishing that a 
pure juice (for Davidou insists on purity as essential) should 
when rapidly evaporated by steam in a copper vessel at a low 
temperature produce a white concrete, the wonder is that a 
system so simple and presenting such advantages, should 
have remained in abeyance till within the last 3 or 4 years, 
when it has been revived by Mr. Fryer in the introduction of 
the Concretor. This last, a modification of the inclined plane 
and cylitider of Davidou, appears to be a wonderful improve- 
ment on the carron coppers, producing in a single concrete 
form, easily made, handled and shipped with little or no loss, 
what was formerly shipped with great trouble as the two 
separate articles, sugar and molasses with an eventual loss 
on their aggregate of seldom less than 12 or 14 per cent. 
Mr. Fryer rates the gain at something over £4 per ton by 
employing the Concretor ; I am inclined to place it much 
higher if the apparatus be worked with care, not that it will 
ever give or was ever intended to give a white concrete like 
