THE ANALYST. 163 OLD PROCESSES OF FOOD ANALYSIS.” BY A. W. BLYTH, N.R.C.S. &V contributing a short paper on behalf of the Society of Public Analysts, with the title of b L OM Processes of Pood AlzaZysis,” I ail1 anticipate the question czGi bolzo ? by answering, that he is a poor student of science, who takes no heed of the road hewn out by his predecessor. While we extend knowledge by new departures, while we pioneer OUT path through the untravoIled forest, cutting away the undergrowth of error, the settlers who preceded us must neither be forgotten nor lightly held :- 33 must, however, be confessed that as the older methods of sophistication were primitive, coarse, and evident, so mere the methods of detection; bread mixed with lnlnps of iron, or made of rotten materials within, good without, needed not the exposition of its quality by recondite or refined processes.A full history of the older methods of assaying foods, beverages and drugs mould be neither more nor less than B history of the evolution of the chemical, physical and natural sciences, for all these aids are used by the modern analyst; the less ambitious aim I adopt of giving a brief aketch of what may be considered the more important labours of the earlier workers of -this particular field. To do this with profit;, I must at once pass over both the writers before the Christian era, and some 16 centuries after that era; the quaint conceits and theories of the herbalists, and of the alchemists, the questions so hotly debated, as to the division of substances into hot cold or ?i&t ; the sdpkw, the Mercwy and the s d t believed at one time to be the basis of all composition, must not detain us.So far anr they suggested or stimulated to experiment, they advanced knowledge, so far as they were accepted as true, they retarded knowledge. One of the earlier pioneers of analysis was the Hon. Robert Doyle; in a way he may be said to have written the first scientific treatis, the sole object of which was to make known a method af detecting adulteration. This work is entitled 61 Xcdiciw Hydv*ostatica ; or, @drostcttios apphkd to Hater& Nedica, showing haw by the weight that divers bodies used in physic have in water, we may diacover164 TEE ANALYST, whether they be genuine or adulterated,” 800 London1 690. His method is of course the one so long known termed ‘( lj”coiJc Grav&.” He showed that impure mercury sub- limate, that Roman vitriol contaminated with alum and other substances could by the method of weighing them &st in air, then in water be detected. The invention of the microscope opened the doors of a previously invisible universe, and by revealing the intimate structure of animal and vegetable tissues, and the regular and mathematical forms of crystals, gave an impetus to all sciences, and among these to the analytical.Anthony ‘van Leuwenhock an4 his contemporaries, Doctors Hooke and Eenry Powers, mere certainly the first who occupied themselves in a aystematic way with the microscopical studies. I am never wearied of insisting on the claims of Leuwenhock, the more so for he has been much neglected, and few people have even a superficial acquaintance with the works of this acute and great observer.Theine, the active principle of both tea and coffee, is said to have been discovered by a German chemist in 1820, but Leuwenhock had separated it 120 years previously, both by crystallisation from coffee infusion and by sublimation of tea leaves; hie description is not quite exact, but he has given a fair drawing of what he calls the (( minute saline particles;” all of them he says ‘( were of the same shape, and long and pointed at the ends.” He, how- ever, was not aware that the crystalline principle of tea and coffee were identical. ‘‘ 1 afterwards endeavoured,” he goes on to say, ( I to discover, if possible, how many Baline particles could he produced from a single leaf of tea, but having reckoned up only a part of the volatile salts contained in on0 leaf 1 forbore any further observations because the number I had already reckoned up was so great that I dared not publish it, as I had proposed to do ; and, indeed, many persons could not believe that the leaf itself could be divided into so many parts, visible by the microsoope, as I aaw volatile aaline parti- cles produccd from.one single loaf,” Leuwenhock also discovered piperine, the crystalline principle in pepper, he distilled pepper and considered that the difference between white and black was that the one was decorticated, the other not, and proved that he was right by direct experiment. He noticod that vinegar could be neutralised by chalk, and described the vinegar eel, The miscroscopical chamcterfl of milk did not escape him, he mid that it was a fluid containing many globules, some of these mere of a buttery nature, and rise to the top, others sunk to the bottom and wore of a different composition.In England Dr. Henry Power and Dr. Hooke were working in the same direction ; they both investigated the minute structure of a number of plants, and Dr. Power pub- lished observations, directly bearing on the detection of adulteration by the microscope, aa for example when ha states how easy it is to observe the mercurial and other sub- stances in compound powders. Food analysis is now seldom performed qualitatively only, but also quantitatively, and the first; attempt at the quantitative analpiis of the more important foods was made in the 18th century.The general process by the school of Boerhave in use was distillation, and all thiugs possible of distillation were submitted to that process,TEE ANALYST. 165 If an 18th century chemist mere by some undiscovered art resuscitated, placed in his old primitive laboratory, and asked to analyse a sample of milk, Be would act as follows:-Some large quantity, many pounds, would be weighed in what we should call a common coarse balance ; he would next take from its special stand with loving care a thick large fantasticallyshaped retort, and place the milk therein ; he then would set it over a furnace, lit by a fire either of charcoal or ordinary materials, he would sit down and match it, keeping the heat as low, and the distillation as slow as possible ; it would take a long time ; was not Voltelenus thirteen days distilling one sample of milk, when the retort cracked and spoilt his labours 3 day by day, with incredible patience, our resuscitated chemist mould sit by his retort and watch (‘ the spirit,” as most volatile condensable matters were called, and when no more moisture could be detected- ho would urge the fire, carbonise the residue, even unto a caput mortzczcm, and lixiviate any s d t s it might contain with water, LastIy this solution would be concentratod and allowed to cry st’allise.Geoffrey, in 1737, made what I believe is the first quantitative analysis of milk, he took 12 lbs,, or about 190 times as much as a modern analyst would use, the milk was coagulated by gentle heating, the coagulum was separated and weighed, and found to be 20 per cont of the original quantity, the serum was evaporated down, rtnd its weight equalled 5.2 per cent.; he carbonised this residue, obtained a caput mortuum and lixiviated certain salts, of these quantitative determinations the solid residue from the serum representing milk sugar, and soluble ash, was what might be expected and is fairly correct; the caseine and milk-€at making up the coagulum, are, of course, much too high. Hoffrnann and Casper Neumann made analysis of milk, and estimated the total solids with accuracy-so that, despite of the clumsy processes, it is clear that had they only forsaken their wearisome distillations, and essayed the use of solvents, the 13th century chemists mould have made a very fair quantitative analysis of milk.The great chemists Stahl Merggraf, Brandt, Bergmann, Schiele Berthollet Priefley and Lavoisier also belong to the 18th century, and laid the foundations of modern chemistry, which were so extended and developed by Liebig and the German school. Modern analysis is so very modern, that several living chemists have pretty well seen its entire growth, sound views as to the constitution of organic bodies, aud accurate methods for the quantitative determination of alcohol, sugar, starch, gum, fat, wax, resines glucosides and alkaloids, all of which, the very root of our operations, are, so to speak, the birth of yesterday. The food analysts since 1874, united in a society, have aimed at the co-ordination and the apeoialisation of existing knowledge, so as to bring it to bear upon the subjects which it is their duty to deal with, and they have done so, with such success, that their nine years of corporate existence can be looked at with pride and satisfaction. There is a great gap between the appliances in the laboratory of Voltelenus; between the painful tedious watching for thirteen days of a distillation, and the rapid yet accurate methods now in um, but there still remains a great deal of work to be done in order to distinguish the true from the false. We. must settle the composition definitely of all genuine subsfancefl, a task requiring many hands and minds and these not morlriiig done, but in co-operation.