Continuous Process EvAPORATORS 167 
on the start, and to finish the evaporation between 90 and 100 
degrees F. The air blast is so intreduced as to keep the milk 
along the heating surface of the jacket and coils im cireulation 
and, therefore. prevent largely the baking of the milk on the 
heating surface. After the milk has been evaporated to a certain 
degree of concentration, say 2:1. it 1s transferred to the auxihary 
evaporating tank where the condensation is completed. This 
transfer is not necessary, but is resorted to solely as a conve- 
nience, in order to continue treatment of the reduced bulk of 
material in a smaller tank and leave the larger tank free for 
treating a fresh batch of milk, and further, because there are 
no obstructing coils in the auxiliary tank. interfering with the 
drawing off of the hnished and thick condensed milk. In this proc- 
ess, as now used, the milk is usually first separated and the 
skim milk only is condensed. ‘The cream is subsequently added 
to the condensed skim milk. 
Advantages and Disadvantages of Campbell Process.—The 
initial cost of installing the necessary machinery is much less 
than where vacuum evaporation is practiced The low heat 
applied makes it possible for the finished product to retain the 
properties of raw milk, leaving the albumenoids and lime salts 
in their original and easilv digestible form and preserving the 
antiscorbutic vitamines in active form. 
This process is applicable only in the manufacture of un- 
sweetened condensed mitk. Unless subsequently sterilized, the 
product will keep for a short time only. This process has at the 
present time only very limited use. It can hardly he considered 
as an impertent braneh of the cendensed milk industry. 
Crraerie RIV, 
CONDENSING MILK BY CONTINUOUS PROCESS. 
The processes of condensing milk described in preceding 
batch- 
principle of evaporation, ‘Phat is in the case of the vacuum pan. 
chapters, are exclusively confined to the intermittent or 
the fresh milk runs into the pan until the capacity of the pan is 
reached and no condensed milk Icaves the pan until the con- 
densation of the entire hatch 1s completed. Then the pan must 
be emptied before more milk can he drawn in. In a similar man- 
ner, in the Campbell process, evaporation of the entire batch 
