SUGAR 925 



the idea of a much cheaper and more practical lamp to burn under water ; how the 

 atmospheric air under pressure in the helmet of the diver, by means of the air-pump, 

 is but partially deteriorated, and M. Pasteur tried to examine whether the remaining 

 oxygen was still sufficient to maintain the light of an ordinary petroleum-lamp. The 

 trial which he made for that purpose succeeded perfectly. On the opening in the 

 helmet, where, by means of the valve, the consumed air escapes into the water, is 

 screwed an India-rubber tube, f -inch diameter and 4 feet long, to which the water-tight 

 lamp was attached. The side on which the air enters the lamp was, as in the helmet, 

 divided in such a way as to prevent the light from being blown out, and to distribute 

 the air, as much as possible, xmder and around the flame. The little valve-spindle, 

 placed upon the helmet to prevent the entrance of the water, was taken away and put 

 on the top of the lamp. Behind the light was placed a parabolic mirror, and on the 

 front side a convex glass ; to the back was fitted a crook to carry the lamp, whether 

 in the hand or on the breast. M. Pasteur had the satisfaction to read with this lamp 

 under water small hand-writing, and observed at the same time that neither the car- 

 bonic acid nor the vapour of water breathed out by the diver had any influence on the 

 illuminating powers of the flame. 



SUCCINIC ACID, or Acid of amber (Acide succinique, Fr. ; Bernsteins'dure, Ger.), 

 was formerly obtained by the destructive distillation of amber, in which process it was 

 accompanied by an essential oil, and a little acetic acid ; it was purified by being 

 precipitated as succinate of lead, which, after being well washed, was decomposed by 

 the equivalent quantity of sulphuric acid ; the solution of succinic acid, thus obtained, 

 was evaporated, and allowed to cool, when the succinic acid crystallised out. It 

 seems to exist ready formed in amber. 



It is easily obtained artificially by acting on stearic or palmitic acid with nitric 

 acid. It also occiirs in the leaves of the wormwood, and in many of the resins of tho 

 pine tribe. It may likewise be obtained by fermentation from asparagin, and from 

 malic acid, malate of lime yielding nearly one-third of its weight of it. 



In order to produce it from malic acid, 3 Ibs. of crude malate of lime are to be dif- 

 fused through a gallon of warm water, and 4 ounces of decayed cheese added to the 

 mixture, which is to be kept at the temperature of 100 for about a week. Carbonic 

 acid is disengaged, whilst a mixture of crystallised carbonate and succinate of lime is 

 deposited, and acetate of lime remains in solution. 



SUCCINITE. Prof. Dana has applied this name to the insoluble resin which 

 forms about 80 per cent, of amber. See AMBEK. 



SUET. The internal fat of the abdomen of the sheep. See TALLOW. 



SUGAR (Sucre, Fr. ; Zuc&er, Ger.) is, with some slight exception, the sweet 

 constituent of vegetable and animal products. It may be distinguished into three 

 principal species. The first, which occurs in the sugar-cane, the beet-root, and the 

 maple, crystallises in oblique four-sided prisms, terminated by two-sided summits ; it 

 has a sweetening power, which may be represented by 100 ; and in circumpolarisation 

 it bends the luminous rays to the right. The second occurs ready formed in ripe 

 grapes and other fruits ; it is also produced by treating starch with diastase or sul- 

 phuric acid. This species forms cauliflower concretions, but not true crystals ; it 

 has a sweetening power, which may be represented by 60 ; and in circumpolarisation 

 it bends the rays to the left. Berthelot has shown that a moderately strong solu- 

 tion of glycerine, in contact with certain animal membranes, is found, after some 

 weeks, to produce a substance with the properties of grape-sugar. One pint of gly- 

 cerine in 10 pints of water is added to the membrane, which may amount to ^th of 

 the weight of the glycerine. The time required is 10 to 12 weeks. If putrefaction 

 begins, it is destroyed. The third variety is found in fruits, and also in sugar which 

 has been long boiled, or heated with acids ; this is called fruit-sugar. Besides these 

 three principal kinds, the sugar of milk, and the sugar of manna or mannite, are 

 found closely allied, and may be called two other species. Allied to these is sor- 

 bine, extracted from the elderberry, and mosite, which occurs in the flesh of animals. 



Sugar, extracted either from the cane, the beet, or the maple, is identical in its pro- 

 perties and composition, when refined to the same pitch of purity ; that of the beet is 

 said to surpass the other two, since larger and firmer crystals of it are obtained from 

 a clarified solution of equal density. Sugar melts at 320 Fahr., and on cooling forms 

 a transparent substance usually called barley-sugar. When heated to between 400 

 and 410 Fahr. it loses two equivalents of water and becomes brown. Sugar thus 

 fused is no longer capable of crystallisation, and is called caramel by the French, and 

 is used for colouring liqueurs. Indeed, sugar is so susceptible of change by heat, that 

 if a colourless sohition of it be exposed for some time to the ternperatxire of boiling 

 water, it becomes brown and partially uncrystalli sable. Acids exercise such an in- 

 jurious influence upon sugar, that after remaining in contact with it for a little while, 

 though they be rendered thoroughly neutral, a great part of the sugar will refuse to 



