March 



1883.] 



IS.X'JOW LEDGE 



135 



mid-iiay on tlio ICth. Slie travels from Pisces into Aries on the 

 I Ith, crosses this constellation into Taurus on the 12th, remains in 

 that constellation during the whole of the 13th and 14th, continues 

 licr course across Taurus on the loth, travelling across the north- 

 eastern part of Orion, and so into Gemini, where wc leave her at 

 the civil noon of March 17, or, as an astronomer might call it, 

 .it h. of March IG. At 4 p.m. on the 15th she is in conjunction 

 «ith Jupiter, at a distance of 3° 12' south of that planet. The one 

 occnltation of a star visible during the period of which we are 

 treating is that of the 6th magnitude one, o Arictis, which will dis- 

 appear at the moon's dark limb on March 12 at C h. 51 m. in the 

 evening, at an angle of 115^ from her vertex, and reappear at lier 

 bright limb at an niv.'Ie of 344" from her vertex at 7 h. 40 m. p.m. 



15READ AND HONEY. 

 I5v Dr. Puevo.st. 



BREAD and honr v ; two foods well knowni to all : the one dry 

 and nearly tasteless, the other soft, sweet, and moist — and 

 apparently very different to one another. Many will be certain to 

 remark, Wliy couple them together ? Surely we shall now see how 

 different they are in their composition, for we know that they are 

 not at all like one another when they are eaten. Such ideas con- 

 cerning the composition of these two foods are veiy erroneous, for, 

 instead of being widely different, they are very closely connected. 

 Tme, there is a difference, to explain which it will be necessarj' 

 to say a few words about the composition of each. Analyses 

 of perfectly dry bre:id show that it is made up of about fifteen 

 parts of nitrogenous matter, of three parts of ash or miner.il 

 matter, and the remaining eighty-two parts may be con- 

 sidered to be starch. Honey, on the other hand, consists wholly 

 of the sugar called glucose, together with a very small quan- 

 tity of cane-sugar, which disappears as the honey gets older, 

 and also a very small amount of ash. Xow, as our jrarpose is to 

 show the connection between sugar and starch, wo vnU neglect the 

 nitrogenous matter and the ash in the bread ; bnt it must not be 

 thou;;ht that this nitrogenous matter is of no conset|uence, for, 

 although not present in large (juantities. still it is very important, 

 as to it the firmness of head is due : so we will think of a loaf of 

 bread merely as a Inmp of baked starch. Having thus reduced 

 our loaf to one kind of substance, which is apparently so dissimilar 

 to honey, it will not be tmintcresting to trace the history of the 

 origin of each. Meal flour, which, as all must be aware, is 

 obtained by grinding down the seed of a cultivated grass, 

 and has been elaborated by means of the leaves and roots 

 of the wheat plant before deposition in the ear; the roots have 

 supplied the nitrogenous matter and ash, while the leaves have 

 produced the starch, as explained in a former article. Much 

 ..in the same way as starch is carried up into the car of wheat, 

 'so is the honey carried upwards and deposited in the nectarj- of a 

 flower, from which it is removed by bees, and stored in the honej-- 

 comb. It is not for u.s to discuss why honey should be formed in 

 flowers, but the reasons are well known, and the purpose is most 

 important. Now, where does the honey come from ? When the 

 ..plant begins to form its flower, which is a preliminary process 

 to the production of fruit and seed, a part of the starch 

 present in the stem becomes soluble, and by reason of certain 

 vital influences, it absorbs a proportion of water, and is 

 converted into glucose ; after that it is deposited in the 

 nectary, together with a very miimte quantity of an odorous 

 fluid, which gives to honey its peculiar flavour. What, now, is 

 the difference between starch and honey ? Why, just a proportion 

 of water, which, by entering into combination >vith starch, effects 

 in it the great change in its properties with which all are familiar. 

 The tasteless starch of the bread, better known as the "crumb," 

 becomes a sweet and often cn.stalline substance bearing no resem- 

 blance whatever to the original material ; and what is more 

 remarkable still, is the fact that both are derived from the carbonic 

 acid of the air, that substance which is obnoxious to man, and 

 which ho is glad to get rid of, from which the carbon, ha\nng been 

 abstracted, is caused to combine with water. These are not 

 theoretical nor suppositional .statements — far from it. A large 

 industrj- for the iiruductioii of sugar (glucose) from potato, 

 starch, and maize exists, and the material obtained is employed 

 for the manufacture of spirit. There are many examples of 

 this kind of change of starch into sugar, the best known being 

 the production of sugar by the sugar-cane and the beet ; this latter 

 kind, which is so largely manufactured in France and Germany, and 

 from thence imported into England, has to a great extent taken the 

 place of the old West Indian cane-sugar. The sugar-beet, which 

 much resembles the ordinary red beet-root, however, contains no 

 starch in the bulb where the sugar is found, so search must be 



made for the source whence the sugar comes. The bulb, on examina- 

 tion, is found to consist of cells inclosing a fluid consisting princi- 

 pally of sugar and water, and the walls of these cells are composed 

 of a substance ternieil celbdiise, whose composition is identical with 

 that of starch, but the properties are very different. Celh.losoin the 

 laboratory of the chemist can be converted into sugar, hut it is 

 not probable that such a change occurs in the beet ; for, though 

 possible, this change has not been detected. The more correct 

 supposition is, and it is one confirmed by observation, that the large 

 leaves of the jjlant. as is the case with other plants, elaborate 

 starch, which, assuming the soluble condition, descends into the 

 bulb, where it is deposited in the cells prepared for its reception; 

 but during its descent it again changes its form, takes up water, 

 aiifl is coiiverteil into sugar, and in then it is that cane-sugar which 

 is ))roduce(l. That this is what occurs naturally is rendered all the 

 more probable by an observation that has been made, which shows 

 that when the plant is in an unhealthy condition, starch is found in 

 the bulb. From this we may, perhaps, infer that the converting 

 powers of the plant have been unable, by reason of ill-health, 

 to change the whole of the soluble starch into sugar; for it 

 must not be forgotten that a certain amount of energy, so to speak, 

 must be exerted to force a proportion of water to combine with 

 starch. A distinction has alwaj-s been drawn Iwtween cane-sugar 

 and glucose, for not only are the proporties somewhat different, 

 but the composition also ; to produce glucose from starch requires 

 the combination of one proportion of water with one of starch, but 

 for the formation of cane-sugar, only a half proportion of water is 

 retpiisite. At the commencement of this article it was stated that 

 loaf of bread consisted of starch and nitrogenous matter ; bnt 

 this is only true so long as the loaf is one of dough, and before 

 it is baked, for when it is put into the oven and heated, the starch 

 begins to change, which is indicated by the formation of the 

 crust. Examination by proper means would show that it 

 no longer consists only of the two substances above mentioned, 

 bnt that a third is now present, namely, dextrine, and dextrine has 

 exactly the same composition as starch. This change may easily be 

 observed by careful heating in, say, an iron spoon over a lamj), a 

 little starch, carefully stiiTing it the while. Soon a change of 

 colour will be noticed, and when this colour, which should be light 

 brown, is even throngh the whole mass, the starch will have been 

 changed into dextrine, which will dissolve with ease in water. This 

 alteration is perhaps the most curious of any that have been, as 

 yet, inentione<l, for in the dextrine we have the same number of 

 particles of carbon, hydrogen, and oxygen as are in the starch. 

 What has happened that the characteristics of starch should be 

 lost, and now ones assumed, we can hardly till, bnt we believe that 

 they have luerely been arranged in a dilferent manner, just as 

 a carpenter can from a piece of wood make either a shelf or a box, 

 whichever he chooses ; the material is the same, and the quantity 

 the same, but^the arrangement is different : so it is with the dextrine 

 and starch ; we might also add, so mth cellulose, which has, it will 

 be remembered, the same composition as starch, but as we cannot 

 produce cellulose from starch by such simple means as are required 

 to form dextrine from starch, the change is hardly so striking. 

 We have now accomplished th'! task before us as far as it was 

 possible in a few words to show the connection between bread and 

 honev; and we hope that when any of our readers next consume 

 these two articles of diet, they will not forget that, putting aside 

 the presence of nitrogenous matter, although their palates discover 

 a considerable difference between the two, the chemist only 

 acknowledges the addition of water to the one to produce the 

 other. 



Tire LoxDo.v LiBR.vRY. — ''If this library," says M. Guizot, "had 

 not existed, I should have felt great inconvenience. It is a very 

 useful library : there are a great many excellent books about 

 English History which I have found there. It is a great inconve- 

 nience to mo to be obliged to go to the British Museum, and not to 

 be able to work in my own room, with my own books ; that is a 

 great part of the pleasure of working." Mr. Leigh Hunt, in his 

 " Stories from Italian Poets," says: — " I cannot, in gratitude for the 

 facilities afforded to myself, as well as for a more obvious and pubHc 

 reason dismiss this preface without congratulating men of letters 

 on the establishment and increasing ])rosperit3- of the London 

 Library, an institution founded for the jnu-pose of accommodating 

 subscribers with such books at their oivn houses as could only be 

 consulted hitherto at the British Museum." Mr. M'Cabe, in tho 

 Preface to his " Catholic Histori;- of England," states that " he has 

 been possessed of one great advantage. As a Member of the 

 London Library he has had access to, and the use in his own home 

 of, a splendid collection of works. On the shelves of that Library 

 he has found most of his authorities, — the ancient monastic writers, 

 and those authors who afford passages illustrating the facts stated 

 by tho chroniclers." 



