98 



• KNOV^LEDGE 



[Feb. 16, 1863. 



simple case of cooking an egg by means of hot water. 

 Tlipse changes are in this case easily visible and very 

 simple, althougli the egg itself contains all the materials of 

 a complete animal. IJoncs, muscles, viscera, brain, nerves, 

 and feathers of the chicken — all are produced within the 

 shell, nothing being added, and little or nothing taken away. 



When we open a raw egg, we find, enveloped in a 

 stoutish membrane, a quantity of glairy, slimy, viscous, 

 colourless fluid, which, as everbody now knows, is called 

 albww'n, a Latin translation of its common name, " tin' 

 V'hile." Within the white of the egg is the yolk, largely 

 composed of that same albumen, but with other constituents 

 added — notably a peculiar oil. At present I will only con- 

 sider the changes which cookery effects on the main con- 

 stituent of the egg, merely adding that this same albumen 

 is one of the most important, if not the one most im- 

 portant, material of animal food, and is represented by a 

 corresponding nutritious constituent in vegetables. 



We all know that when an egg has been immersed 

 daring a few minutes in boiling water, the colourless, slimy 

 liquid is converted into the white solid to which it owes 

 its name. This coagulation of albumen is one of the most 

 decided and best understood changes effected by cookery, 

 and therefore demands especial study. 



Place some fresh, raw white of egg in a test-tube or 

 other suitable glass vessel, and in the midst of it immerse 

 the bulb of a thermometer. (Cylindrical thermometers, 

 with the degrees marked on the glass stem, are made for 

 such laboratory purposes.) Place the tube containing the 

 albumen in a vessel of water, and gradually heat this. 

 When the albumen attains a temperature of about 134° 

 Fahr., white fibres will begin to appear within it ; these 

 will increase until about 160° is attained, when the whole 

 mass will become white and nearly opaque. It is now 

 coagulated, and may be called solid. Now examine some 

 of the result, and you will find that the albumen thus only 

 just coagulated is a tender, delicate, jelly-like substance, 

 having every appearance to sight, touch, and taste of being 

 easily digestible. This is the case. 



Ha\iug settled these points, proceed with the experi- 

 ment by heating the remainder of the albumen (or a new 

 sample) up to 212°, and keeping it for awhile at this 

 temperature. It will dry, shrink, and become horny. If 

 the heat is carried a little further, it becomes converted 

 into a substance which is so hard and tough that a valuable 

 cement is obtained by simply smearing the edges of the 

 article to be cemented with white of egg, and then heating 

 it to a little above 212°.* 



This simple experiment teaches a great deal of what is 

 but little known concerning the philosophy of cookery. It 

 shows in the first place that, so far as the coagulation of 

 the albumen i^ concerned, the cooking temperature is not 

 212°, or that of boiling water, but 1C0°, i.e. •'32° below it. 

 Everybody knows the difference between a tender, juicy 

 steak, rounded or plumped-out in the middle, and a tough, 

 leathery abomination, that has been so cooked as to shrivel 

 and curl up. The contraction, drying up, and hornifying 

 of the albumen in the test-tube represents the albumen of 

 the latter, while the tender, delicate, trembling, semi-solid 

 that was coagulated at 160°, represents the albumen in the 

 first. 



But this is a digression, or rather anticipation, seeing 

 that the grilling of a beefsteak is a jjroblem of profound 

 complexity that we cannot solve until we have mastered 



• " EKg-comenti" 'made by thickeniiif,' white of ogg with finely- 

 powdered quicklimq, has long been used for mending alabaster, 

 marble, &c. For joining fragments of fossils and mineralogical 

 specimens, it will be found very useful. White of ogg alone mav 

 be- used, if carefnllv heated afterwards. 



the rudiments. We have not yet determined how to prac- 

 tically apply the laws of albumen coagulation as discovered 

 by our test-tube experiment to the cooking of a breakfast 

 egg- 



BICYCLES AND TRICYCLES FOR 1883. 



Bv John Bkowxixo, 

 (C/iairinan and Treasure/f of the Loiidmi Tricycle Club.) 



^pHE novelties in bicycles offered for the coming season 

 i are as yet but few. There has again been a decrease 

 in weight in racing machines. Two full-sized bicycles were 

 exhibited at the Albert Hall, one weighing 1 9 lb. and 

 the other 21 lb. One, a 54-inch, made by the Coventry 

 Machinists Company, I examined carefully. The work- 

 man.ship was excellent, and, notwith.standing its wonderful 

 lightness, I have little doubt it is capable of standing the 

 strain it will be required to bear. 



A contrivance for preventing a rider from taking a 

 header over the handles deserves mention on account of 

 its noveltj'. Many of my readers have probably seen 

 public performances by trick riders on bicycles. In some 

 cases in such exhibitions, the riders take the handles 

 off the machines and ride without them, steering 

 and balancing entirely by their feet. The handles of 

 the machines fit on a square on ths top of the head. 

 The new arrangement I am describing is similar in 

 construction, but, on being pressed firmly down, the 

 centre or socket of the handle locks itself on a square 

 spindle projecting from the head by means of a 

 strong spring. Underneath the handle-bar there are two 

 long, light levers. Upon pressing either of these upwards, 

 the spring is released, and the handle-bar can be removed. 

 The reason a rider goes over the front of a bicycle when 

 anything checks his machine, is because he instinctively 

 grasps the handles tightly. But in falling forward on a 

 machine fitted as I have described, a rider's thighs would 

 be brought into contact with the levers below the handles, 

 these are lifted, and withdraw the spring-catch, and con- 

 tinuing the pressure, force off the handle-bar. The rider 

 then falls on his feet, with the handle-bar in his hands. 

 I would much rather see the inventor exhibit the action 

 of this contrivance than experiment with it myself. 



Kinnaird's new crank action, made by Keen it Co., of 

 Norwood, is an elliptical motion of the pedals attached 

 by two levers to the cranks. A pedal, with eight inches 

 leverage, rises and falls only about four and a half inches. 

 The mere saving of the unnecessary motion will represent 

 a great saving of power in riding. This very ingenious 

 contrivance admits of many applications. By its aid a tall 

 man may ride a small bicycle, or a short man may ride a 

 large bicycle. But probably its most important applica- 

 tion will be to tricycles, as it will enable them to be 

 driven without either chains or levers. 



Having referred to such novelties as I believe will prove 

 useful in bicycles, I will return to improvements in tri- 

 cycles. And first I will refer in more detail to those 

 machines I so briefly alluded to in my last article. 



Of the llumber tricycle, I need only say that there seems 

 but little room left to improve this machine, either for 

 grace, speed, or lightness. I do not regard the machine as 

 the best for general adoption. The machine known as the 

 Lady's Humber, however, I can thoroughly recommend as 

 one of the lightest, best, and safest front-steering machines 

 made, equally adapted for ladies or gentlemen ; and I 

 would strongly urge its makers to bring it more promi- 

 nently before the public. 



