SUPPLEMENT. 



689 



De Laval, centrilugal force brings the cream to the surface and to the top, where it is met 

 by a sharp tube, fixed from the outside and literally cut off, the tube acting like a plane 

 and making a furrow into which the band of cream rushes only to be cut off the faster. 

 It rushes down this tube and out into the pail set to catch it. As the milk continues 

 to be poured in and the cream to be cut off, the skim milk at the back is forced 

 through an outlet at the top into a little chamber above the cream, where it is taken by 

 a cutting tube in a similar manner. 



With regard to Professor Fjord's apparatus, it may be mentioned that if all the cream 

 were required, a plain tube only would be necessary; but as different milk producer's 

 and dealers have their own ideas, they must be consulted. One may wish to make 

 cheese, and leave a portion of the fat in the milk; another may prefer to sell skim milk 

 which is still rich in cream, for there is no denying the fact that tSis separator takes more 

 cream from it than can be obtained by any old system. For this end, then. Fjord's reg- 

 ulator is used, and by its aid any proportion of fat can be taken. Thus if the supply be 

 increased by regulating the tubes, the skimmer will only take thesame quantity of cream, 

 consequently more must be left in the milk. 



The last addition to this machine is an ingenious machine by which the revolutions 

 are counted, and this does Mr. Peterson, who is really the inventor of the machine, great 

 credit. This gentl^man claims to skim with his large machine 1,200 poundsor 120 gal- 

 lons an hour. This statement is not an exaggeration, for, when in Sweden, the manager 

 of a large factory, where the centrifuge is worked, in answer to a question told us that 

 he separated 200 Swedish cans an hour, this can being 6 pounds. The cream, too, can 

 he taken of any thickness, so that indeed a spoon will stand upright in it. 



The large machine costs 1,100 kroner Danish, or about JE60, while the smaller is 650 

 kroner, this revolving nearly 2,800 a minute, skimming nearly 600 pounds of milk, and 

 working by one horse. There is also a tube which will carry the skim milk away over- 

 head into a vat, instead of into a pail below. It should be mentioned that in all cases 

 the temperature of the cream and the quality of the milk has much to do with the re- 

 sults, and to this end it is now the custom to heat al Imilk to its temperature on leaving 

 the cow by passing It over hot water or steam tubes as it runs into the machine. 



In comparing this machine with the Laval, we find, first, that it requires less power 

 and does more work, its surface speed being 9,750 feet, or 5,250 less than the Laval. It 

 can be had in almost any size, and can be regulated. At the Eoyal trial it gave more 

 butter, while the analysis showed — 



During the past year the most important contest which has yet taken place was held 

 at the Danish Exhibition in Aulborg where prizes were offered for large and small sepa- 

 rators. The Danish of Petersen easily won in the large class, two of his machines com- 

 peting, one running at 1,900 and the other at 2,100 revolutions per minute, the in- 

 dicated horse-power being 1.3. In the small class the jury selected the Danish and the 

 Laval for trial at a farm-house under the superintendence of Professor Fjord. Every- 

 thing was done which science could devise to make the experiment complete. Every 

 minute during the trials the speeds of the axle, of the horse gear, of the vertical 

 axles, of the separators, of the rotary dynamometer, and of the intermediate motion, 

 were written down by self-registering indicators. The Danish gave a speed of 2,400 to 

 3,000 per minute, and the Laval 5,600 to 7,000, the result of the five series of experi- 

 ments which were made being that where both separators were driven by the same power 

 the Danish skimmed 565 pounds (Danish pound is equal to 1.12 pounds English) per 

 hour, leaving 2C per cent, of fat in the skim milk, and the Laval 450 pounds per hour, 

 le?.ving 24 per cent, in the skim milk ; or, in other wfirds, it was shown that at the same 

 ,^^,«*^aegree of skimming and with the same supply of milk the Laval required one-third more 

 power than the Danish, or, supposing that the same power is consumed , the Danish small 



H. Ex. 51 44 



