700 APPENDIX A 



the market from the milk-drying machine illustrated on Plates 

 CCXIII. and CCXIV., as a result of unskilled or careless 

 management, there is no doubt that by judicious and expert 

 handling, milk can now be relieved of all but about 6 per 

 cent, of its moisture without appreciably altering, or in any 

 way injuring, the milk residue as food even for infants. It 

 has been thoroughly tested, chemically and bacteriologically, 

 at the Carnegie Laboratories, and under the supervision of 

 the Officers of the Board of Health of New York. Hundreds 

 of children of from five days to two years old have been fed 

 with it. It has been shown to be "absolutely sterile and 

 indefinitely preservable." In the stomach it coagulates 

 into small, easily assimilated, granular particles like human 

 milk, and is not liable to form large indigestible clots like 

 ordinary cows' milk. The mechanism is quite simple. " Two 

 polished metal cylinders, 28 inches in diameter by 5 feet 

 long, are mounted parallel in a solid framework, and 

 separated from each other about an eighth of an inch. They 

 revolve inversely, making six turns per minute. Above 

 them is placed a small box for holding the milk, in contact 

 with a main reservoir, which feeds each box through a supply 

 pipe. Steam, from the boiler of the engine producing the 

 driving power, and at a pressure of three atmospheres, is intro- 

 duced into the cylinders, the surfaces of which are thereby 

 heated to a temperature of between 2 20 x 2 30 F. The 

 liquid milk to be dried is allowed to fall in thin streams 

 upon the heated revolving cylinders, and its water is rapidly 

 evaporated." Each cylinder becomes covered with a thin 

 layer of milk solids in a soft condition, which is removed 

 by two fixed knives or scrapers nicely adjusted in close 

 proximity to the surfaces of the revolving cylinders. The 

 work is facilitated by a pad of steam which forms between 

 the surfaces of the cylinders and the milk, and thus prevents 

 it being scorched at the high temperature, at which, but for 

 this mechanical protection, milk would readily assume a 

 burnt flavour and odour. The heat of the subjacent rollers 

 almost instantaneously dries the soft film or continuous sheet 

 to a solid condition, and it subsequently falls, in a brittle con- 

 dition, into the receiving box. On being put through a sieve 

 to reduce it to a uniform powder resembling a coarse flour, it 

 is ready to be made up in moisture-proof tins or bags for 

 transport to market. It is only one-eighth the weight of 

 liquid milk, and it can be immediately restored to the liquid 

 condition by the addition of hot water at about 170 F. For 

 cooking purposes it is most serviceable, being always at hand 

 without risk of acidity. In all the industries in which milk 

 is used it has proved successful ; for example, for bakers, 



