GLUCOSE. 



351 



prepared stones with a stream of water. The 

 meal is next passed into a trough, the bottom 

 of which is made of fine bolting-cloth, where 

 the starch is washed through, after which it is 

 led to large tanks and allowed to settle. After 

 being beaten up with caustic soda to effect a 

 separation of the gluten, the starch is again 

 allowed to settle in long, shallow troughs. 

 Having been washed free from all adhering 

 alkali, it is next beaten up with water into a 

 cream and conducted into the converting- tubs, 

 which are made of wood, and are supplied 

 with coils of copper steam-piping. In these 

 the starch-cream is treated with dilute sul- 

 phuric acid, and steam is allowed to bubble up 

 through the mixture from small holes in the 

 copper pipes. This is the " open-conversion " 

 process, and is completed in about two hours. 

 In the " close-conversion " process, which oc- 

 cupies about fifteen minutes, the substances are 

 inclosed in stout copper cylinders, and sub- 

 jected to the action of superheated steam. The 

 conversion is sometimes accomplished by fer- 

 mentation, but this process requires a much 

 longer time. The "open-conversion" method 

 is the more usual one. After conversion the 

 acid that has been used is neutralized by mar- 

 ble-dust, or by the carbonate of baryta and 

 animal charcoal. The liquid is then filtered 

 through cloth and animal charcoal, and is con- 

 veyed to the vacuum-pan, where it is evaporated 

 at as low a temperature as possible, till the re- 

 quired degree of concentration is reached. If 

 grape-sugar is to be made, the process of con- 

 version, instead of being stopped as soon as the 

 starch has disappeared, is carried on still fur- 

 ther to a point which can be determined only 

 by trial. After concentration, the liquid is 

 conveyed into tanks, where the process of so- 

 lidification is accomplished after several days. 

 The sirup - glucose will not harden, except 

 partially, and after many months, whatever the 

 degree of concentration may be short of that 

 necessary for the formation of sugar. Glucose 

 and grape-sugar are sometimes bleached with 

 sulphurous acid, but the practice is objection- 

 able on account of the liability of that acid to 

 form by oxidation free sulphuric acid, and leave 

 it in the product as a dangerous impurity. 

 Glucose, as formed in the earlier stages of the 

 process, may be considered as a mixture of 

 several chemical substances, among which are 

 dextrine, genuine glucose, and a substance iso- 

 meric with cane-sugar; and it is on account of- 

 the presence of the last substance that the 

 poorly converted glucoses are sweeter than the 

 well converted. 



Glucose is used chiefly for the manufacture 

 of table-sirups and candies, for brewing, as 

 food for bees, and for artificial honey. The 

 actual amount of it employed for any of these 

 purposes can only be estimated, for its use is 

 unpopular, and manufacturers are unwilling to 

 give information on the subject. It is certain- 

 ly used extensively and in an increasing degree 

 in brewing, where the artificial product may 



be made to take the place of the glucose which 

 is naturally developed in malting. All soft 

 candies, wax, and taffies, and a large propor- 

 tion of stick-candies and caramels, are made 

 of glucose. Very often a little cane-sugar is 

 mixed in to give a sweeter taste to the candies, 

 but the amount of this is made as small as pos- 

 sible. The glucose which is made for this 

 purpose is much thicker and denser than the 

 ordinary glucose, it having a specific gravity 

 that may reach 1*440, with a percentage of 

 water as low as 6'37. A large percentage of 

 all the glucose made is used in the manufacture 

 of cane-sirups. In this manufacture, the glu- 

 cose is mixed with some kind of cane-sugar 

 sirups until the tint reaches a certain standard, 

 the amount of the latter substance varying 

 from three to ten per cent, according to cir- 

 cumstances. These sirups are graded accord- 

 ing to the depth of the tint, as "A," "B," 

 " C," etc., and are sold in the shops under va- 

 rious fanciful names. It is said that by reason 

 of their cheapness, and their acceptable quali- 

 ties, they have driven all the other sirups out 

 of the market. Glucose is very extensively 

 fed to bees, which eat it with great avidity, 

 and store it away unchanged as honey. It is 

 also put up directly in trade as honey with 

 which bees have had nothing to do being 

 put by means of appropriate machinery into 

 artificial combs made of paraffine. Glucose is 

 also employed in the preparation of condensed 

 milk, and small quantities of it are used by 

 vinegar-makers, tobacconists, wine-makers, 

 distillers, mucilage-makers, and for some other 

 purposes. 



. Grape-sugar is also used for most of the pur- 

 poses to which glucose is applied, but chiefly 

 for the adulteration of other sugars. When it 

 is reduced to fine powder it can be mixed with 

 cane-sugar in any proportion, without altering 

 its appearance, and, as it costs less than half 

 the price of cane-sugar, the adulteration is im- 

 mensely profitable. 



The question whether glucose is deleterious 

 as an article of food, which has been much dis- 

 cussed in the press and in public bodies, is 

 answered, by those who have given the subject 

 a scientific examination, in the negative. In 

 chemical composition, glucose is identical with 

 the natural sugars of fruits and honey which 

 are universally accepted as wholesome foods. 

 According to Professor W. S. Haines, of Rush 

 Medical College, it differs from cane-sugar, so 

 far as its physiological action is concerned, in 

 that cane-sugar, when eaten, has to be con- 

 verted into glucose before it can be assimilated, 

 while the glucose itself is already in a condi- 

 tion to be assimilated directly. Professor 

 Harvey W. Wiley, who has given special atten- 

 tion to the subject, and has read a paper upon 

 it before the American Association for the 

 Advancement of Science, does not hesitate to 

 say that a glucose which is properly made is a 

 salutary article of food, and that there is no 

 reason to believe that when thus manufactured 



