Aug. 17, 1»S3.] 



♦ KNOWLEDGE ♦ 



99 



Rendus of that period. In Vol. 71, page 3G, M. Boillot 

 describes his method of mixing kitchen-stuH' and other 

 refuse fat with lime-water, agitating the mixture when 

 heated, and then neutralising with an acid. The pro- 

 duct thus obtained is described as admirably adapted for 

 culinary operations, and the method is applicable to the 

 purpose here under consideration. 



Further on in the same volume is a " Note on Suets and 

 Alimentary Fats " by M. Dubrunfaut, who tells us that the 

 most tainted of alimentary fats and rancid oils may be 

 deprived of their bad odours by "appropriate frying." 

 His method is to raise the temperature of the fat to 1 40" 

 to 150° Centigrade (284° to 302° Fahr.) in a frying-pan ; 

 then cautiously sprinkle upon it small quantities of water. 

 The steam carries oft" the volatile fatty acids producing the 

 rancidity in such as lish-oils, and also the neutral ofl'ensive 

 fatty matters that are decomposed by the heat. In another 

 paper by M. Fua this method is applied to the removal of 

 cellular tissue of crude fats from slaughter-houses. It is 

 really nothing more than the old farmhouse proceeding of 

 " rendering " lard, by frying the membranous fat until the 

 membranous matter is browned and aggregated into small 

 nodules, which constitute the " scratchings " — a delicacy 

 greatly relished by our British ploughboys at pig-kUling 

 time, but rather too rich in pork fat to supply a suitable 

 meal for people of sedentary vocations. 



The action of heat thus applied and long-contiiiued is 

 similar to that of the strong sulphuric acid. The impuri- 

 ties of the fat are organic matters more easily decomposible 

 than the fat itself, or otherwise stated, they are dissociated 

 into carbon and water at about 300° Fahr., which is a 

 lower temperature than that required for the dissociation 

 of the pure oil or fat (see No. 13 of this series, July Gth). 

 By maiutaining this temperature, these compounds become 

 first caramelised, then carbonised nearly to blackness, and 

 all their powers of ofiensiveness vanish, as such ofteiice is 

 due to slow decomposition of the original organic com- 

 pounds, which now exist no longer, and the remaining 

 caramel or carbon cinders being quite inofl'ensive or no 

 further decomposible by atmospheric agency. 



In the more violent factory process of purification by 

 sulphuric acid the similar action which occurs is due to the 

 powerful aflinity of this acid for water ; this may be strik- 

 ingly shown by adding to thick syrup or pounded sugar 

 about its own bulk of oil of vitriol, when a marvellous com- 

 motion occurs, and a magnified black cinder is produced by 

 the separation of the water from the sugar. 



The following simple practical formula may be reduced 

 from these data. When a considerable quantity of much- 

 used frying fat is accumulated, heat it to about 300° F., as 

 indicated by the crackling of water when sprinkled on it, 

 or, better still, by a properly constructed kitchen thermo- 

 meter* graduated to about 400° F. Then pour the melted 

 fat on hot waici'. This must be done carefully, as a large 

 quantity of fat at 400° poured upon a sma'l (juantity of 

 boiling water will illustrate the fact that water when 

 suddeidy heated is an explosive compound. Tlie quantity 

 of water should exceed that of the fat, and the pouring be 

 done gradually. Then agitate tin; fat and water together, 

 and, if the operator is sufliciently skilful and intelligt^nt, 

 the purification may be carried further by carcifully boiling 

 the water under the fat, and allowing its steam to pass 

 through ; but this is a little dangerous, on account of the 

 possibility of what the practical chemist calls " bumping," 

 or the sudden formation of a big bubble of steam that 



* I liavo a vaKi'O impression of having seen sucli iin instrument 

 advertised, but cannot remember where, or by what maker. It may 

 bo worth his wtiilo to benplit tlio readers of Kxowi.Ki>ciE, .and him- 

 self, by re-advertising therein, with particulars of price, &c. 



would kick a good deal of the superabundant fat into the 

 fire. 



Whether this supplementary boiling is carried out or 

 not, the fat and the water should be lefc together to cool 

 gradually, when a dark layer of carbonised impurities will 

 be found resting on the surface of the water, and adhering 

 to the bottom of the cake of fat. This may be peeled off 

 and put into the waste grease-pot, to be further refined 

 with the next operation. Ultimately the worst of it will 

 sink to the bottom of the water. Then it is of no further 

 value, and will be found to be a mere cinder. 



HOW TO GET STRONG. 



KEDUCING FAT. 



I HAVE received through the editor several letters re- 

 lating to preparations — some patent medicines others 

 ofl'ered in the form of prescriptions — for reducing fat with- 

 out change of regimen or increase in the amount of exercise 

 taken daily. Of all these preparations it is to be observed 

 that they are advertised solely to make money. In every 

 single case which has thus far been brought under my 

 notice, the unfortunate heavy weight is invited to spend a 

 large sum of money in the purchase of many bottles of 

 some preparation in order that he may after many 

 weeks find his weight notably reduced. Either the 

 medicine is oflered without any account of its ingre- 

 dients, or in reply to letters the advertiser gives 

 a prescription such as no chemist would be likely 

 to mix, and such as the advertiser asserts that few chemists 

 can mix properly even if willing. In one case, the 

 corpident are told in so many words that a number of 

 bottles of the medicine are to be bought and consumed 

 before any good efl'ects will begin to be recognised. In the 

 other the advertiser seems to ort'er a prescription gratis ; 

 but it comes really to the same thing ; he knows that 

 the persons who answer his advertisement will apply to 

 him for the medicine, and in the cases which have come 

 under my notice he asks a monstrous price for a prepara- 

 tion prolialjly qiiite worthless and possibly (when used as 

 recommended in large quantities) most mischievous. As 

 to the value of any medicine for reducing fat, it should be 

 noticed that only a long course of experiments conducted on 

 a great number of persons, and under very various condi- 

 tions, could possibly prove that a preparation was a specific 

 against obesity, — and certainly no such experiments have 

 been made in the case of any of the advertised medicines. 

 If there were any medicine by which fat could certainly 

 be diminished in a few weeks or months, it is almost certain 

 that the constitution would be injured far more seriously 

 by the medicine than it had been by obesity ; and whereas 

 undue fat can be removed by patient perseverance in health- 

 giving regimen, the mischief done to the constitution by the 

 long-continued use oi noblrums for reducing fat would pro- 

 bably be permanent. Unquestionably it is most unwise for 

 persons troubled with obesity to use any nostrum without 

 medical advice ; and 1 believe no medical man would advise 

 the use of any one of the advertised cures for obesity. 



1 return to the \arious measures which a sensible person 

 anxious to reduce fat without impaii-iug the general health 

 may use with advantage. 



We come now to the measures by which tlie healthy 

 action of the skin may be encouraged, and so fat reduced 

 through increased perspiration. Exercise of course en- 

 courages perspiration, but I am for the moment speaking 



