12. ~Investigation of Milk and Cream Chocolate.~ The tests bearing on these products really constitute a chapter in themselves, which has acquired special importance owing to the great popularity they enjoy and the consequently greatly increased production. According to the unanimous opinion of the Association of German Chocolate Manufacturers and the Free Union of German Food Chemists, expressed when considering the respective claims of such chocolates, it is chiefly if not exclusively a matter of determining the percentage of milk or cream, which ought not to be below 12·5 or 10%, always supposing the milk or cream to be a substitute for sugar, and this means therefore that the quantity of cacao material in the chocolate product should on no account sink below 32%. (Cf. p. 283 No. 3. Abs. 5.) The method employed in the investigation is generally the same as that suggested by Laxa in his treatise on “Milk Chocolates”[197] although it has been considerably improved by Baier and his colleagues.[198] It is here a matter of working backwards from the determination of the fatty and nitrogenous components (or caseine) to the amount of milk or cream in the chocolate. This presents a certain amount of difficultly as it is not only necessary to determine the milk, but also to establish that neither skimmed or whipped material (either in part or entirely) has been employed. Yet it is possible here to proceed with absolute certainty, as Baier[199] convincingly demonstrates, by taking into consideration the relative proportion of milk fat, called caseum or caseine. If it is desired finally to characterise the respective chocolates, determinations of the ~quantity~ of milk fat present and the amount of milk product used become essential. Baier gives both as calculable (cf. footnote 1)[200], the Reichert-Meissl number of the total fat being ascertained, and from this, subtracting the R.-M. number of the cacao fat present[201] the quantity of milk fat, finally the amount of caseine, milk sugar, mineral matter and other factors. No details of this somewhat extensive calculation are proved in the original.[202] We give the following regulations (Laxa-Baier) for carrying out the determination of the caseine, together with the necessary formula.