THE CHEMISTRY OF COOKERY. 223 



men 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 fibers will 

 begin to appear within it ; these will increase until about 160 is at- 

 tained, 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. 



Having settled these points, proceed with the experiment by heat- 

 ing the remainder of the albumen (or a new sample) up to 212, and 

 keeping it for a while 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 touo;h that a val- 

 liable cement is obtained by simply smearing the edges of the arti- 

 cle 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 is concerned, the 

 cooking temperature is not 212, or that of boiling water, but 160, 

 i. e., 52 below it. Everybody knows the difference between a tender, 

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

 ery 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 represent the albumen of the latter, while the tender, delicate, 

 trembling, semi-solid, that was coagulated at 160, represents the albu- 

 men in the first. 



But this is a digression, or rather anticipation, seeing that the grill- 

 ing of a beefsteak is a problem of profound complexity that we can 

 not solve until we have mastered the rudiments. We have not yet 

 determined how to practically apply the laws of albumen coagulation 

 as discovered by our test-tube experiment to the cooking of a break- 

 fast-egg. Knowledge. 



* " Egg-cement," made by thickening white of egg with finely-powdered quicklime, 

 has long been used for mending alabaster, marble, etc. For joining fragments of fossils 

 and mineralogical specimens, it will be found very useful. White of egg alone may be 

 used, if carefully heated afterward. 



