SINCE its introduction by Lloyd in 1895 in the south-western counties of England, the determination of the acidity of the whey exuding from the curd has been regularly used by cheese-makers as a means of tinmig the manufacturing operations. The acidities are generally expressed as percentages of lactic acid in the whey. During the later stages of the process, it is found frequently that there is a fall in acidity in the whey, more especially after the salt has been added. No valid explanation has been put forward for this fall in acidity, apart from the obvious ones, namely, that the whey after salting is diluted with fat and salt and the acidity might be expected to fall.