(the late) C. H. F. FULLER and A. V. BELL X-ray diffraction patterns and infra-red spectra have shown that although the lactose in spray-dried milk powder is normally in the amorphous state, it can sometimes be present as the crystalline a-monohydrate, or in an unusual crystalline form.Studies have been made of the absorption and subsequent loss of moisture in humid atmospheres by (a) spray-and freeze-dried milks, and ( b ) spray-and freeze-dried lactose prepared from lactose solutions. I t is shown that milk powders exposed to these conditions generally contain a-lactose monohydrate, but the spray and freeze-dried lactose produce a mixture of the a-monohydrate and the ,!?-anhydride.For identification purposes all the known crystalline forms of lactose have been prepared and studied by X-ray diffraction and infra-red methods, and it has been found that the above-mentioned unusual crystalline form of lactose found in some milk powders is the anhydrous molecular compound consisting of a-lactose and ,!?-lactose in a molar ratio of 5 : 3. This compound gives an X-ray diffraction pattern which is different from, but an infra-red spectrum similar to, those of the stable &-lactose anhydride.

The gencrnl probletn of preetlicting package perforrnnttcc cnn be illustrnted by the following example. The itnngiunry ninterial to be pncked is a wheat product which when pncketl ltas 10% moisture, and which begins to mildew a t 17%. The packets nre to be stored in nn ntniospltere of 96% 1Z.H. The niirtcrinl bulks 50 Ib. to thc bushel, nud is to be packed in pounds (413 g. oven-dry weight). 1 Ib. of the ninterinl would occupy about 530 c.c., so that n conveniently sized piickct would be 9 x 9 x 9 cui. I n calculnting the overall pcrnienbility of any pnckngc it is desirnble to niensiire X, Y, and Z for the niaterinls to IN used, under the conditions which are expected. ~Vlien the niensurenients nrc applied, however, to estimnte the side shelf-life of the pnckngc, n rensonahle safety factor must be uged to nllow for vnrintions ; so if it is not possible to innkc thc niensurcnients, nn upproxintntc rnluc may be ol)tained by using the results quoted above. I t is consitlcred thnt unclcr nonnnl conditions-no clraught, niotleriite tempcrnturc, humidities not cstreme-this \voiild incorporate n snfety fnctor of nl)out ten.If the pncknge is ntntle froin nioisturcproof cellulose filni, by Iientscnling, in tlie form of n 9-ciu. cube, the totnl area will be 6 x 0.092 or 0*0#36 sq. ni. Tlie heat-scnls will be in strips 6 nini. wide, aud the length niny be tnken as that of four sides of the packet, so thnt tlic nrea inodificd by heat-senling (p) is 4 x 0.09 x 0.006 or 0.00216 sq. in. Then by diffcrcncc the uiiultered men, a, is 041614 sq. ni. The length of the folds (8) is tltnt of 12 edges, or 1.08 nictres. From the rnlucs of Y and Z given nlrovc, S = 0.2, Y = 9 . 5 , and dey/nim. If the packet hnd beeu made from siiuilar film, but sealed with nn aillicsire seal 5 nitti. {ride, uitd inensuring 18 x 10 x 8 ctii., it can be estimntcd thnt 1' = 0.0097 + 0.0133 4-0.0017 = 0.0245 g./dny/ntni. KO figures nrc nrnilable yet for other wrnppiitgs, but if it isassumed that tlie overnll pernieal)ility is proportioual to the permeability of the plain wrapping, P for a 9-c1n. cubical packet made from waxed glnssinc would be 0.223 g./tlay/nini. Thc nbovu figures include n lprge safcty factor, but they itre 1111 calculated for cotuplctc exposure. In prncticc the packets would be stacked togctlier, nnd even the most exposed oncs-those at the corners-would only * This work WUII uridurhkcn ut tho mqocst of Dr. J. C. Drummotid, BcientMoAdviaor to tho Ministry of Food.

Against glycerol. Temp. not stated 25 ml. water (sac). 1000 ml. milk. Time 2 days. Preservative toluene 20 ml. whole milk (collodion sac). 25 ml. water. Time 84 hrs. Temp. "ice-chamber" 25 ml. water (collodion sac). 1000 ml. milk. Time 2 days. Preservative toluene 10 ml. milk (collodion or parchment sac). 5 ml. water. Time 24 hrs. Temp. not stated. Preservative toluene

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