The best process for analytical purposes is the one proposed by Sachsse.[151] In this method the starch is heated with the hydrolyzing mixture in the proportion of three grams to 200 cubic centimeters of water and twenty of hydrochloric acid of 1.125 specific gravity, containing five and six-tenths grams of the pure gas. The heating is continued for three hours on a steam-bath. Maercker recommends, instead of the above procedure, heating for two hours at gentle ebullition in an oil-bath. In this method three grams of the starch are reduced to paste with 200 cubic centimeters of water, and then boiled for two hours with fifteen cubic centimeters of hydrochloric acid of 1.125 specific gravity. The erlenmeyers in which the hydrolysis takes place are heated in an oil-bath and are provided with reflux condensers made of long glass tubes on which some bulbs have been blown, as shown in the accompanying figure. In all cases after hydrolysis the solution is neutralized, made to a standard volume and an aliquot part, after filtration, diluted to contain an amount of dextrose suited to the use of the table by Allihn for calculating the percentage of sugar. In diluting the solution preparatory to the estimation of dextrose, it is well to remember that nine parts of starch will furnish theoretically ten parts of dextrose. Since three grams of the sample are used, containing approximately eighty-five per cent of starch, the quantity of dextrose present is a little less than three grams. The solution should therefore contain not less than 300 cubic centimeters. =187. Factor for Calculating Starch from the Dextrose Obtained.=—If all the starch could be converted into dextrose without loss, the quantity of it could be easily calculated theoretically on the supposition that the formula of starch is (C₆H₁₀O₅)ₙ. The factor by this assumption is, starch = dextrose × 0.90. If the starch have the formula assigned to it by Nägeli, _viz._, C₃₆H₆₂O₃₁ the formula becomes, starch = dextrose × 0.918. Ost prefers to work by Sachsse’s method and to use the factor 0.925 to convert the dextrose into starch.[152] In view of all the facts in the case it appears that the analyst will reach nearly correct results by converting the starch into dextrose by heating for three hours at 100° with hydrochloric acid or for two hours at gentle ebullition as directed above, determining the resultant dextrose and multiplying the weight thereof by 0.92.