July 1. 1898.] 



KNOWLEDGE, 



137 



The agricultural labourer is too poorly paid often to aft'ord 

 lean fresh meat, but the nature of his occupation enables 

 him to consume a quantity of hard cheese such as would 

 be impossible for persons engaged in the more highly paid 

 but sedentary occupations. 



The effect of rookiiui is, in the first place, to soften the 

 food, and thus render it easier to masticate. The heat may 

 be applied as dry heat as in roasting, or moist heat as in 

 steaming, but in either case the large quantity of water 

 which is contained in all foods makes the various processes 

 of cooking largely a matter of steaming. This assists the 

 softening of the fibres, ('ire. Another important change 

 produced by the action of heat is the solidification of the 

 albuminous material which forms so important a con- 

 stituent of lean meat and of the other flesh-forming foods. 

 The coagulation of the albumen is familiar to all in the 

 process of boiling an egg, the boiling temperature being 

 necessary in order that the white shall " set." The same 

 setting of the albumen in meat occurs at the surface of the 

 meat during the roasting of a joint. In this process, in 

 which the object is not to extract but to retain all the 

 goodness of the meat, a fierce heat is at first applied all 

 round the surface of the joint. This solidifies the albumen 

 near the surface of the joint. The joint is then moved 

 rather further from the tire, and cooked at a somewhat 

 lower temperature. A great deal of water evaporates from 

 the meat, but most of the juices are confined in the joint 

 by means of the bag or sack of coagulated albumen. If 

 the joint were kept too near a hot fire after the first coating 

 of coagulated albumen has been formed the coagulation 

 would go on throughout the join:, and the meat would 

 become hard and indigestible. When a well-cooked leg of 

 mutton is cut it is full of juices, which flow out readily. 

 If the joint had been put down before a slow fire, and at 

 some distance from it, the water drawn out of the joint by 

 the heat would have carried with it much of the juice and 

 of the fat which should be kept in by the coagulated 

 albumen. In those processes of cooking in which the 

 object is to extract the juices from the meat, the coagulation 

 of the albumen has to be avoided. In cooking starchy food, 

 such as potatoes, the most important change produced by 

 the heat is the swelling up and bursting of the starch 

 granules, producing a light and floury consistency, a 

 change which is necessary if starch is to be digestible. In 

 order to effect this bursting of the starch granules, a 

 temperature as high as boiling point of water must be 

 used ; hence the rule that vegetables always require, for a 

 part of the time of cooking at any rate, a high temperature 

 equal to that of boiling water, but that meat should, as a 

 rule, be cooked at a temperature below that of boiling 

 water. 



ON SOME RECENT INVESTIGATIONS OF THE 

 GEOLOGY OF THE PUNJAB SALT RANGE. 



By G. W. BuLMAN, M.A., B.Sc. 



THE Salt Range is one of the many special features of 

 interest in Indian geology : many new geological 

 ideas are suggested by a study of its various 

 formations. In the rocks of the Salt Range, 

 Dr. Waagen made his important discovery of am- 

 monites associated with pradtirtits, spirifer, stn'ptorlu/nchus, 

 &c. — in other words, they contain rocks of carboniferous age ; 

 in them Dr. Oldham found indications of a palieozoic ice age 

 in India, in the form of the celebrated boulder bed. In 

 them, again. Dr. Warth has discovered the first remains 

 of tfilohitcs yielded by Indian rocks, and in the Salt 



Range the almost universal break between the paheozoic 

 and mesozoic rocks is absent ; carboniferous rocks pass 

 up without interruption into triassic. 



Among the more special features of interest in the rocks 

 of the Salt Range may be mentioned : (I) the clear and 

 unbroken succession of the different systems, uncomplicated 

 by igneous intrusions, and unobscured by metamorphism 

 or crumpling ; (2) the distinctness of the sections owing 

 to the absence of vegetation, and the well-marked colours 

 of the different formations ; (8) the occurrence in the 

 carboniferous system, along with its own characteristic 

 fossils, of iimmirnitex, and the distinctly triassic form 

 crnititi'.s : (4) the peculiar nature of certain beds — as, for 

 example, the palseozoic boulder clay known as the boulder 

 bed, and the salt marl. 



Two interesting and very suggestive papers on these 

 rocks were published in the " Records of the Geological 

 Survey of India ' for 1891. 



In tlie first of these, Mr. Jliddlemiss refers to the vivid 

 impression produced by the first sight of the wonderful 

 features of the Salt Range, where in a single section the 

 eye can take in a series of sharply-defined formations, 

 ranging from paheozoic to tertiary, and following each 

 other in apparently unbroken succession ; where we may 

 see series of strata as free " from the dust of time as an 

 uncut volume fresh from the binder's hands." One of the 

 main objects of Mr. Middlemiss's survey of the Salt Range 

 was to verify Dr. Warth' s discovery of fragments of 

 trilobites [conocephnlites and oleniix) : and this was fully 

 accomplished, fragments of trilobites and brachiopoda 

 having been found, fixing the age of the rocks in which 

 they occur as Cambrian. A remarkable fact about these 

 ancient rocks is that, in spite of their great age, they have 

 been unaffected by disturbances of the earth's crust during 

 the whole of the enormous period which has elapsed since 

 their formation. 



The more important features in the two papers referred 

 to are the investigations of the lower bed known as the 

 salt marl. 



In the " Manual of the Geology of India," the remarkable 

 resemblance of this formation, with its thick beds of rock 

 salt, its gypsum, and its anhydrite, to the trias of our own 

 country is pointed out, and a similar origin suggested. In 

 other words, this salt marl, of probably Cambrian age, is 

 supposed to have originated in a salt lake or lakes. The 

 main point in Mr. Middlemiss's interesting paper is the 

 total rejection of the marine hypothesis, and the suggestion 

 that the salt marl has originated from what may be termed 

 smothered volcanic action. 



Mr. Middlemiss notes the following points which seem 

 to be inconsistent with the idea that tbe salt marl is of 

 Cambrian age and of sedimentary origin : — 



1. Its soft and homogeneous nature. 



2. The absence of definite stratification. 



3. Its method of occurring mixed up with different 

 formations. 



4. The occurrence on the other side of the Indus of 

 other salt-bearing beds, only a short distance off, and yet 

 supposed to be of tertiary age. 



In its structure and composition the salt marl is a 

 remarkable formation. It is a soft red marl, associated 

 with immense masses of rock salt and gypsum. Except 

 where it encloses masses of dolomitic rock, or where 

 associated with beds of gypsum and rock salt, it never 

 shows any signs of stratification, or traces of divisional 

 planes. Keen even in large masses on the hill-sides it shows 

 no structural planes ; nor does it exhibit any trace of 

 colour banding. Another peculiarity is the absence of 

 grains of sand and pebbles of foreign origin, which shows 



