ORGANIC ANALYSIS. 



ORGANIC ANALYSIS. 



102 



means of a small valve placed above the hole, by which tlus second 

 part receives the supply of air. There is also a valve which should 

 remain open, and beside it another valve applied to a hole for the pur- 

 pose of discharging the air from this part of the bellows. A very 

 simple mechanism is employed for opening this latter discharging 

 valve (no matter of what size the opening may be) and of shutting the 

 other, so as to stop the communication with the other part of the 

 bellows. By means of this mechanism, when the smaller bellows has 

 discharged itself into the greater, the power of the latter is nearly 

 doubled. It is worked by the same pedal which applies the trembling 

 sound, and the same pedal also acts upon the swell-box containing the 

 second series of pipes. These three movements are so arranged, that 

 in depressing lightly the pedal, it acts only upon the mechanism of the 

 trembling sound attached to the pipes acted upon by the first series of 

 stops, and makes that note only vibrate ; by depressing the key to the 

 second stop the power of the note is greatly increased, and by then 

 depressing the pedal further the note still increases in power ; finally, 

 when the pedal acts upon the mechanism of the expansive bellows, it 

 gives a great volume of sound. The reverse process gradually dimi- 

 nishes the sound, but to reduce it to pianissimo, another pedal or lever 

 under the key -board, worked with the knee (and hence called a genual), 

 shuts some of the jalousies or lower-boards of the case enclosing the 

 first series of pipes, and by this means the note is further diminished 

 in force. These jalousies are disposed like those for the second series 

 of pipes, but with the difference that in their state of repose they are 

 open. 



ORGANIC ANALYSIS is the generic term for a great number of 

 chemical and physical operations, that have for their object the ascer- 

 taining of the composition and constitution of all matter that has been 

 formed under the influences existing in animal and vegetable life. It 

 also, of course, includes the similar examination of all derivatives and 

 artificial imitations of the matter referred to. 



In illustration of the above definition of organic analysis, let us 

 suppose that we have for examination some well-known fruit, such as a 

 pear. By processes presently to be described, we separate and isolate 

 from it the matter or matters that appeal to the eye, in other words 

 the colouring agent; similarly we obtain the odoriferous principle; 

 then a matter that has no odour, but a distinct and well-defined taste ; 

 next we chemically dissect out the framework or skeleton ; and finally 

 turn our attention to the great mass of substance with which the 

 framework is filled in. Operations are next undertaken by wbjch we 

 assure ourselves that the bodies thus separated are neither more nor less 

 than what we suspect them to be ; uniformity is here the great character- 

 istic. Solid or liquid, the body in question must have a constant specific 

 gravity ; taste, odour, touch, must be unvaried ; to the eye, alone or 

 aided by the microscope, the appearance of each observable particle 

 must be identical ; if a fusible solid, it must have a constant melting 

 point ; if a volatile liquid, its boiling point must be unvarying. The 

 next genes of operations acquaints us with the number of elementary 

 substances contained in each body under examination, as well as with 

 the exact per centage amounts of those elements. Having now, to a 

 certain extent, a knowledge of the composition of the bodies, we arrive 

 at their probable constitution by a process of analogical reasoning ; and 

 this is confirmed or disproved by severally subjecting them to powerful 

 chemical reagents. Possibly the latter cause the substances to 1 

 into two or three bodies of more simple constitution ; if so, they each 

 lie passed through the prescribed ordeaL The odoriferous 

 principle, for instance, of the pear has been isolated in a state of purity, 

 and has been found to contain certain constant centesimal amounts of 

 three elements ; but on farther chemical examination it breaks up into 

 two compounds, each of whk-h however is found to possess uniform 

 properties, and to have a constant centesimal composition. And now, 

 individualized and given character to each of the bodies under 

 examination, we probably recognise them as old acquaintances, or 

 possibly take to ourselves the merit of having discovered new ones. 

 Our ]>ear would yield us such bodies as water, starch, lignin, sugar, 

 Ac. ; the flavouring principle, or essence of pears as we might call it, 

 being found by the latter part of the examination to be a compound of 

 acetic acid and oxide of amyl, or shortly the acetate of amyl. Several 

 f tin- bodies enumerated may be artificially produced, their identity 

 with the natural products being established by the similarity in their 

 physical and chemical characters, especially as evidenced by their 

 per centage composition. 



from what has already been stated, it will be observed that organic 

 analysis is either jimsimate or ultimate. The appearance and behaviour 

 of bodies when acted upon by various reagents or tests may, when 

 viewed by an experienced eye, be sufficient to establish their individu- 

 ality, and their presence and even amount, in the matter originally 

 operated on, may thus be satisfactorily determined : such is proximate 

 organic analysis. But perhaps the bodies in question have no well- 

 marked properties, or are possessed of characteristics not before observed 

 in any known substance ; in either case the number of their elementary 

 constituents must be discovered, and the amount of each element 

 ascertained ; and such is ultimate organic analysis. Ultimate analysis 

 also forms, as it were, the court of appeal from the decisions arrived at 

 in | -in. tim.it*: analysis. 



nic analysis and inorganic analysis are conventional divisions of 

 chemical analysis. Each is subdivided into proximate and ultimate, 



and either one of the four classes is qualitative or quantitative in the 

 sense of those words already alluded to under CHEMICAL ANALYSIS. 

 The line of demarcation that separates these divisions is not very sharp ; 

 many bodies being found in animals and vegetables in a state not dis- 

 tinguishable from that in which they exist in the inorganic kingdom ; 

 such, of course, demand inorganic analytical treatment. Other bodies 

 require modifications of organic or inorganic analysis, according to the 

 nature of the substances with which they are associated, and from 

 which they are to be isolated. The broad principles, however, of in- 

 organic and organic analysis are pretty well defined, and the difference 

 between them easy of practical recognition. While, on the one hand, 

 inorganic analysis comprehends the manipulatory processes connected 

 with the examination of metals and their salts : organic analysis, on 

 the other hand, includes only operations which aid in discovering and 

 investigating the apparently innumerable series of compounds formed 

 by the union, in various ways, of the four elements carbon, oxygen, 

 hydrogen, and nitrogen. 



Proximate Organic Analysis. 



This is by far the more difficult branch of organic analysis. An 

 animal or vegetable substance usually contains a much greater number 

 of proximate principles than the most complex mineral ; these principles 

 have been built up by the agency of that mysterious aggregation of 

 influences sometimes, though very unphilosophically, termed vital 

 force ; and, inasmuch as organic matter is necessarily only examined 

 after those influences have been withdrawn, it follows that there is a 

 constant tendency, as in all dead animal and vegetable matter, to return 

 to its original more simple and stable condition. In addition to this 

 source of complication, the bodies in question being held together by 

 such weak affinities, are not only more readily acted upon and altered 

 by the agents employed by the chemist to separate them, but very 

 frequently act upon each other ; so that, indeed, the perfect proximate 

 analysis of organic matter is, in the present state of our knowledge, an 

 impossibility ; and the various published processes, professing to give a 

 means of arriving at that desirable end, must be looked upon as being 

 merely provisional. We are, however, able to isolate very many 

 proximate principles, and it is quite admissible to include in an analysis 

 such substances as " extractive matter," " balsamic matter," " resinous 

 matter," " ethereal, alcoholic, aqueous, or alkaline extractive," &c., 

 provided always that it be remembered that such names are only pro- 

 visional, and that in future times, as in times gone by, an increasing 

 number of definite principles will probably crop out from such 

 collective substances, and finally their names be altogether expunged 

 from proximate organic analysis. 



We are indebted to Rochleder for the latest improvements in this 

 department of chemistry. The process may shortly be stated as 

 follows. (For further details see ' Pharmaceutical Journal ' for 1860.) 



The organic matter is first mechanically disintegrated. The more 

 points of contact presented by a solM to the. solvent action of a liquid, 

 the better it is ; so that comminution cannot well be carried too far. 

 Often a certain degree of moisture renders the material tenacious and 

 elastic, so that it is difficult of pulverisation ; in that case a careful 

 drying suffices to bring it into a pulverisable condition. Sometimes 

 oily bodies cause the same kind of tenacity, and then expression of the 

 cold or slightly warmed material will expedite matters. In other cases 

 appropriate solvents may be used for the removal of bodies causing 

 tenacity, and disintegration thus facilitated. If pulverisation cannot 

 be accomplished by stamping or rubbing, recourse may be had to 

 rasping, slicing, &c. Obviously much will depend upon the charac- 

 teristic properties of the substance operated upon, so that no general 

 rule can be laid down ; at the same time, however, the above hints 

 may give an idea of the methods to be adopted. 



The material in a fine state of division is now divided into several 

 portions, and each treated with a solvent, in order to obtain a number 

 of extracts, which are to be submitted to farther examination. 



One portion is boiled with water in a distillatory apparatus, by which 

 a decoction and a distillate are obtained ; the former will contain non- 

 volatile constituents soluble in water, the latter volatile matters only. 

 Another portion is treated with cold water, in order to dissolve out 

 such matters as would be coagulated by the hot water. A third portion 

 is heated in water acidulated with sulphuric acid, organic acids being 

 thus set free and dissolved, and sulphates of alkaloids also extracted. 

 The fourth operation is digestion in water rendered alkaline by 

 ammonia, and for this the residue of the first operation may be em- 

 ployed. A fifth portion is subjected to the solvent action of alcohol, 

 either cold, hot, strong, or weak, according to the nature of the material 

 under examination; fats, oils, resins, and many bodies insoluble in 

 water being thereby dissolved. The sixth process consists in treating 

 with ether, which much resembles alcohol in its powers of solution, 

 but differs in its action upon free fatty acids, and one or two other 

 important bodies. 



In addition to the above solvents, others are employed for special 

 operations, as circumstances seem to indicate. Thus the alcohol or ether 

 may be used in an acid or alkaline condition, as described for water; 

 and benzole, chloroform, bisulphide of carbon, and similar liquids, may 

 also be pressed into service under certain circumstances. As before 

 stated, much must depend upon the knowledge, judgment, and obser- 

 vation of the experimenter. 



