103 



ORGANIC BASES. 



ORGANIC BASES. 



100 



present in the organic substance remains in the boat as ash, and may 

 readily be removed and examined. 



Volatile liquids may be burnt in either of the above modifications of 

 combustion tube, but are first inclosed in little bulbs having thin necks 

 that can easily be broken. 



With substances not readily burnt, chromate of lead is sometimes 

 used in the place of oxide of copper. 



Nitrogen may generally be detected in an organic body by the odour 

 of ammonia which is evolved when a little of the substance is heated 

 in a test-tube with hydrate of potash. It is estimated on the same 

 principle by the following arrangement of apparatus. A combustion- 

 tube drawn out to a point, as already described, is charged with soda- 

 lime in the place of oxide of copper. Soda-lime is made by slaking 

 lime with strong solution of caustic soda, evaporating to dryness, and 

 heating to redness. The same precautions are observed as before 

 detailed, but instead of a chloride of calcium tube and potash bulbs, a 

 three-bulbed piece of apparatus, of the annexed form, is attached to 

 j-jj j_ the open end of the combustion-tube, 



i and is charged with moderately strong 



\ hydrochloric acid. The acid absorbs 



the ammonia that is evolved on gra- 



(L dually heating the tube to redness; 



residual ammonia being driven into 

 the acid by a current of air drawn 

 through the whole arrangement in the 

 manner already indicated. If nitro- 

 gen be present in an organic substance 

 it is liable, when burnt with oxide of copper, to pass off in the state of 

 acid-oxides absorbable by potash, hence the estimation of carbon and 

 hydrogen must only be proceeded with after a small bundle of copper 

 turnings have been placed just inside the combustion-tube ; this, when 

 heated to bright redness, effects the decomposition of the oxides 

 into non-absorbable nitrogen and oxygen. 



So much for the practical operations connected with ultimate organic 

 analysis. The weights of the chloride of calcium tube and potash- 

 bulbs having been ascertained, both before and after the combustion, a 

 few simple calculations suffice for ascertaining the percentage amounts 

 of the elements present. These calculations will perhaps be most 

 easily described by an illustration. Suppose that sugar were the 

 substance experimented on, then : 



Quantity of sugar tain 4-75 grains. 



Potash apparatus 



781-13 

 773-82 



After experiment 

 Before 



Carbonic acid 



7-31 



Chloride of ctlcium tube- 

 After experiment 220-05 grains. 



Before 333-30 



Water 



2-74 



7-31 grains carbonic acid contain 2-0313 grains of carbon. 

 2-75 water contain -30S4 hydrogen. 



Or, in one hundred parts 



Carbon 



Hydrogen 



Oxygen (by difference) 



42-55 

 6-43 



51-02 



100-00 



The percentage of nitrogen is calculated from somewhat different 

 data. The acid liquid in the bulbs containing chloride of ammo- 

 nium, formed by the combination of the ammonia with the hydro- 

 chloric aci'l, is placed in a small capsule, bichloride of platinum added 

 t<> it, the whole evaporated to dryness over a water-bath, the residue 

 wished with a mixture of alcohol and ether, and the insoluble crystals 

 of the double chloride of platinum and ammonium collected upon a 

 tared filter and weighed: 220-52 grains of such crystals contain 

 14 grains of nitrogen, their weight, therefore, and the amount of the 

 substance operated on being known, the percentage quantity of nitrogen 

 contained in the matter under examination is easily calculated. 



To determine the equivalent or combining proportion of an organic com- 

 )H,ui>d necessarily forms an important part of the labours of an 

 analyst, and cannot be deduced merely from the data yielded by the 

 operations that have been described. It is, however, ascertained with 

 tolerable ease, if the compound can be made to unite and form a definite 

 salt with some body, the combining proportion of which is already 

 well known. An analytical operation having then shown how much 

 of the well-known body is thus introduced, an easy calculation indicates 

 how much of the organic compound would combine with one equi- 

 valent of the other matter, and this number is obviously the combining 

 proportion of the organic compound. This point having been obtained, 

 tical considerations and the data obtained from combustion 

 conduct to a formula for the compound submitted to organic analysis. 



OBQANIC BASES. Under the definition of the term BASF, the 

 organic txuti - or the basvs derived from animaU and vegetables have 



been alluded to. The source, preparation, properties, &c., of these 

 natura abases or alkaloids are detailed under their respective names, 

 [CINCHONA, ALKALOIDS OP ; CONINE ; NICOTINE ; Nux VOMICA, ALKA- 

 LOIDS OF; OPIUM, ALKALOIDS OP, &c.] The artificial organic bases 

 have not been so fully described, and indeed iu most cases only curso- 

 rily noticed in the article on the body from which they are derived. 

 The present article will therefore be devoted to a description of the 

 modes of formation and general properties of the artificial organic 

 bases, prefaced by a brief review of the probable constitution of the 

 organic bases generally. 



A prominent characteristic of organic bases is the presence of nitro- 

 gen ; they all contain nitrogen. The nitrogenous principles in animals 

 are, of course, directly or indirectly obtained from vegetables ; and the 

 nitrogen in vegetables is known to be derived from ammonia. Nearly 

 all artificial organic bases are actually built up from ammonia ; and, 

 moreover, artificially or naturally formed, they all retain the character 

 of basicity, which is the chief chemical property of ammonia. Follow- 

 ing then such strong presumptive evidence, chemists have of late years 

 referred the organic bases to the simple typical body ammonia, and 

 have in most cases succeeded in showing how they are constructed 

 upon, or at all events derived from, the type NH 3 (aminet). Berzelius 

 was the first to suggest that the basic character of the alkaloids was inti- 

 mately connected with ammonia. To the prophetic sagacity of Liebig, 

 however, are we indebted for the idea that they were derivatives of 

 ammonia; that they were, in fact, amidogen bases or ammonia (NH 3 ) 

 in which an equivalent of hydrogen is replaced by an electro-positive 

 radical. Following out this idea Wurtz succeeded in obtaining several 

 such bodies ; but it is chiefly to the remarkable and laborious investi- 

 gations of Dr. Hofmann that we are indebted for the very complete 

 knowledge which we possess of this interesting class of organic com- 

 pounds. 



A minet, is a frequent collective title of the organic bases that are 

 derivatives of NH 3 . The amines may be: 1. Monamines ; 2. Dia- 

 minei ; 3. Triaminea ; 4. Tetramines ; or, 5. Pentamines, according as 

 they seem to be constructed upon a single, double, triple, quadruple, 

 or quintuple atom of NH 3 . 



1. Monamines. This class is constructed upon a single typical atom 



1 



of ammonia, namely, H vN. Primary monamines contain only one 



H J 



of the three atoms of hydrogen (H) replaced by a radical (R) ; their 



R] 

 general formula is therefore H \ N. Secondary monamines contain 



two atoms of radical, thus, 



H 



T ; and moreover the radicals may be 



similar or different ones. Here we get the first glimpse, and a very 

 faint one, too, of the inconceivable numbers of organic bases that 

 possibly exist ; for of twenty radicals the first may be occupying the 

 place of one equivalent of hydrogen in a secondary monamine, while 

 each of the remaining nineteen successively occupy the place of the 

 other equivalent of hydrogen, a new organic base being each time 

 produced. Similarly the second of the twenty radicals may be keeping 

 its place, while the remaining eighteen are consecutively introduced, 

 and another batch of bases formed ; and thus with only twenty simple 

 radicals nearly two hundred secondary monamine bases may be ob- 

 tained. But there are many more than twenty radicals, and each 

 successive one would of course introduce a greater number of changes, 

 and produce, therefore, a greater number of compounds than its pre- 

 decessor. Moreover each simple radical possesses its own chlorine, 

 bromine, iodine, peroxide of nitrogen, &c., derivative, and of course 

 each of these might keep its place in a secondary monamine, while 

 innumerable changes were being rung upon the second radical. Indeed 

 it is useless endeavouring to pursue these calculations farther; we 

 have only got into the second of twelve classes, and already view such 

 a number of organic bases as would defy the powers of the most zealous 

 experimenter to produce and examine. When, again, it is remembered 



R> 

 that the next class, the tertiary monamiues R > N must contain a far 



R) 



greater variety, an indistinct notion can be obtained of the number of 

 changes that may take place in the still higher classes. The general 

 formula; of the monamines are obviously six : 



/. 



R , M 



IN 



R'"}N 



a. Primary monamines, sometimes called amidogen loses, such aa 



ethylamine > N. 6. Secondary monamines, like diethylamine 



C.H S ) C,H 6 ) 



C 4 H 5 > N. c. Tertiary monamines, e.g. triethylamine C 4 H S > N. 



H ) C 4 H, ) 



d. Secondary monomines or imidoyen baiee, as they have occasionally 



