WINE-MAKING IN CALIFORNIA. 281 



maxima explains why the highest temperature found in the 

 single-frame process was considerably (4) behind that 

 observed in the three-frame process (No. 558), where the 

 whole mass reached its most intense action simultaneously, 

 although a slight occurrence of the reversal of temperatures is 

 observable here also. It should be noted that (as stated in 

 the table) the latter process was not entirely normal in its 

 .course, a portion of the pomace that should have stayed 

 below the frames having been carried through the meshes to 

 the surface by the ascending gas, thus equalizing the temper- 

 ature throughout the mass much more than would have been 

 the case had the pomace cap been of sufficient thickness under 

 each frame, or the meshes of the frame fine enough to pre- 

 vent the skins from rising to the surface. 



Where the single frame only was used, scarcely a grape 

 skin was seen on the surface ; and except toward the last, the 

 maximum temperature was always found near the lower layer 

 of the pomace cap. During the last two days a white scum 

 was seen to gradually form on the surface of the wine, and in 

 the end gathered into -white mould islets, as was observable 

 under the microscope. No such scum was to be seen on the 

 three-frame tank, which had remained covered during the 

 whole process, except while the temperature was being taken. 



Marked differences in the course of their fermentation is 

 also apparent in two tanks that were subjected to /outage, or 

 stirring, viz. : Nos. 560 and 561. The one which was left 

 open to the air, and also received an extra amount of stirring, 

 fermented with a violence greater than any of the others ; so 

 that in order to prevent a wholesale running over of the froth 

 and serious loss, it became necessary to fasten down on it a 

 cover for four hours. The maximum temperature of 95 was 

 not, however, reached until about eighteen hours later, al- 

 though the pomace cap at the depth of seven inches showed 

 101 after the violence subsided. The action and tempera- 



