Survivor curves show that, under conditions likely to be found in practice, hypochlorite solutions of low alkalinity disinfect milk films on surfaces more rapidly than those of greater alkalinity.

Dehydration of the milk film results in slower disinfection rates by both neutral and alkaline solutions.

Increasing the milk content in the film reduces the rate of disinfection and reduces the effect of the neutral solution to a greater extent than the alkaline.

Although it is known that several phage races, capable of developing on a certain strain of Streptococcus cremoris, exist in the surroundings of commercial cheese factories in New Zealand, only one specific race is invariably isolated from cheese or cheese whey when the culture is used as a starter. Laboratory and field evidence suggests that this particular race has a special affinity for the organism, and that its presence interferes with the growth of other races which could develop in its absence.

Determinations of hardness were made on 324 samples of butter drawn monthly for 3 years from nine factories distributed throughout New Zealand. The results were compared by statistical methods with the iodine values and softening points of the corresponding butterfats which had been determined by Cox & McDowall(4). It was shown that the softness (reciprocal of hardness) was significantly correlated with both iodine value and softening point, which together explained 55 % of the variation in softness observed. Of the remaining variation, 59% was due to seasonal changes other than those in iodine value and softening point and 36 % to differences between factories. It is considered that manufacturing variations were responsible for very little of the seasonal variations, and that the differences between factories were due as much to district differences as to manufacturing differences. It is concluded that only a small part of the variation in softness of the butter samples was due to manufacturing variations, and that at least 80 % of the variation could be attributed to differences in the raw material.

An experiment is described in which ratings on some 200 cheese made on 31 different days were rated for firmness, quality, springiness and crumbliness, both when 2 weeks and 8 weeks old. Some of the relationships between the ratings are discussed, in particular the ratings for firmness and quality. By means of the firmness ratings made on the cheese at 2 weeks, twenty-eight cheese out of 211 could have been screened off, and of these twenty-eight, nine were subsequently seriously down-graded for quality. Only two cheese which were not screened off developed unsatisfactorily to the same degree. Individual differences between judges are noted, especially with regard to quality. The cheese-maker considers the cheese to be about 1 point higher in quality (on a 7-point scale) than the remaining judges. One judge who criticizes adversely about three times as many cheese as the remainder of the judges also down-grades about six batches of cheese which are not down-graded by the remaining judges.

1. Hypochlorite was allowed to react with glycine and with skim milk in various proportions, and the germicidal power of the resultant mixtures was determined.

2. The results indicated that chloramino compounds formed by interaction of hypochlorite and protein or amino-acid have a definite but slow disinfecting action against Str. cremoris.

3. The chloramino compounds did not appear to be more strongly germicidal at pH 9·5 than at pH 7·0 under the conditions of the experiments.

This note gives particulars of a method of determining the solubility of roller-dried milk powders which has been in use in the Department of the Government Chemist for some years. The figures obtained are empirical but are found to be a valuable aid in the comparative assessment of quality. The method is not claimed to be highly original, but appears to have aroused sufficient interest to justify publication. It is used in the Department for roller-dried milks only. For spray-dried powders a method is employed which measures the volume of deposit given on centrifuging similar to the Solubility Index test of the American Dry Milk Institute.