104 



It will develop the ferment, but good judgment is required to obtain the 



right degree of acidity by smelling, tasting, and testing its strength. It 

 should have a certain degree of density, show the formation of small 

 granules, and have a clear sharp taste. Keject it if it smells or tastes 

 badly, and does not thicken properly. As soon as approved the fermen- 

 tation must be stopped by immersing the can containing it into cold 

 water. From 3 per cent, to 5 per cent, of this ferment is added to the 

 cream barrel after the top of the ferment has been thrown away, as it 

 may contain injurious bacteria from the short exposure to the air. This 

 method is not always satisfactory if the dairy buildings or the surround- 

 ings are impregnated with injurious bacteria, which are sure to infect 

 the new ferment and cause it to fail. 



Fourthly, the pure cultures of the beneficial bacteria, isolated and cul- 

 tivated in bacteriological laboratories, are thoroughly safe to give a first 

 class butter, and are in common use in Denmark. Presently they will 

 be introduced into all the large dairies in the United States of America, 

 and, although the local consumption there will absorb all the first class 

 product for some time to come, we should not lag behind. Professor 

 Conn has now isolated bacterium No. 41 from the best June butter, and 

 by inoculating winter cream with it, has been enabled to impart the 

 June flavour and other fine qualities to the butter produced from it. Ex- 

 pert bacteriologists will soon be able to isolate and cultivate bacterium 

 No. 41 for the use of dairies all over the States. In Denmark the pure 

 cultures were also obtained from the finest butter, but, whilst in one la- 

 boratory they separate only two beneficial bacteria, others isolate and 

 cultivate several. 



The purchasers are instructed how to apply these bacteria to the 

 cream. One laboratory sells its ferment in bottles holding about a pint, 

 which must be used all at one time The pure culture is added to a 

 small portion of sterilised milk or cream, and then set aside at a given 

 temperature until it has attained the proper stage. It is then further 

 propagated in more milk or cream, and when a sufficient quantity has 

 been obtained it is added to the cream in the barrel, where it effects the 

 necessary fermentation in eighteen to twenty hours. Up to the time of 

 Professor Greorgeson's visit the ferment could not be perpetuated outside 

 the laboratories for any length of time, and it will always be a matter 

 of greatest care to isolate the beneficent from the harmful bacteria. This 

 work will probably have to be left to specialists. The pure cultures are, 

 however, reasonably cheap, and may become cheaper with the increas- 

 ing number of bacteriological laboratories. At the Bell Springs Cream- 

 ery, Professor Georgeson tri< j d samples which he had purchased from 

 Mr. Quist, and they had a decided influence on the butter, the quality 

 of which was superior to any previously made there, although the cream 

 had not been sterilised. The cultures had to be specially prepared for 

 their transit to Kansas, being on the road from the 10th March until 

 the 5th June. One was in milk sugar, and one in a nutritive fluid of 

 Mr. Quist's invention. In Denmark, where these cultures are only a few 

 days prepared before use, they are cultivated in skim milk. It is to be 

 hoped that Christian Hansen, who has now established a branch of his 

 laboratory in America (or some other bacteriologist) will start one in 

 Australia. 



In order to obtain the finest quality of butter, that will keep well, the 



