17,2 Adriano: Determination of Lactose 217 
per sulphate * solution and 8.8 cubic centimeters of 0.5 sodium 
hydroxide solution. After the addition of the alkali the mixture 
must still have an acid reaction and contain copper in solution. 
Fill the flask to the 500 cubic centimeter mark; mix, filter 
through a dry filter, and determine the lactose in the filtrate, 
taking 50 cubic centimeters for the copper reduction and 10 
cubic centimeters for the alkaline potassium permanganate 
method. 
For the optical method the directions given in Sherman’s 
Organic Analysis(9) were followed. 
The results of the analysis performed on canned and on fresh 
cows’ milk are as follows: 
TABLE 3.—Determination of lactose in milk. 
{Figures express the percentages of lactose by weight.] 
Sample. Lactose. 
Polaris- | Quisum- | so .nlet’s 
No, Description, cope. Ber method, 
Per cent. \|Per cent, |Per cent. 
1 | Sterilized Norway natural milk_____....-......--_---.--.- 4.60 6.21 5.65 
2 BBs Sisiaaner saps ak NS 2 Pacrrecn pe igrt npn ocala cy See ns Jaana Ce, Otc eee - 4,56 5.20 5.64 ° 
Average___._ AS pine. Ung aoe RP rca nee OS 4.580 5.205 5. 645 
8 | Sterilized evaporated milk -.__.____- ; athectguecdorid 6.12 9.52 9.76 
ad Wc ee eae ee ee ea Arta 8.26 9. 88 10.08 
a5 AE a EERE game! = SEGRE yay Saag eipiatabe. St aide. Pee ea 7.28 9.70 9. 88 
a6 TG ic ee a ee ze 1.22 9.84 9.86 
BNGUEIO oc oie wencns aie Gewminpadeauean 7. 220 9. 735 9. 895 
7 | Evaporated milk 8.71 9.98 10.30 
8 Do ieee eae peg hae eeeae 8.78 9.99 10.24 
9 Db St Ac tse eee wee 8.72 9.94 10.30 
10 65553). SiS5j. AER Lee eee nabs, 9.94 10.29 
ARORA GRE. chsh 5 at 8. 736 9.962 | 10.282 
11 | Sterilized natural milk ace 4.41 4.50 4.52 
19 Den caddis. catkiiadk ieecs bales ees 4, 42 4. 46 4.62 
13 ee ee ies 4.38 4.53 4.46 
14 16. eee si bee 4.88 4.46 4.73 
Average. 5 ane 4.395 4. 487 4.582 
4.50 4.80 5. 08 
4.48 4.79 | 6.06 
Se 4.490 4.795 | 5.070 
8, but they were treated with varying 
® These samples were taken,from the same can as No. 3, 
amounts of pure lactose. The percentage of lactose added was subtracted to find the true 
percentage of lactose in the milk. 
2 Dissolve 34,639 grams of copper sulphate in 100 cubic centimeters of 
water and dilute to 1 liter. 
