ART. XXI.-On the Relation of the Chemical Constitution of Bodies to Taste; by Prof. E. N. HORSFORD, of Harvard.* PROF. HORSFORD alluded to a paper upon Glycocoll published in 1846, in which he called attention, in a note, to the interesting relation sustained by that body in its chemical constitution, to other sweet bodies, and cited the following formulæ : C4H3O3 Glycocoll. Sugar of lead. Pb. C4H303 0 H C1H3O3 × 3 = Grape sugar. C4H3H O3Oxyd of glycerile To this enumeration of sweet bodies was appended the query, "Is this similar taste dependent upon a similar arrangement of their minutest particles?" Prof. H. remarked that, early in 1848, he presented to the American Academy of Arts and Sciences, with a modification of the formulæ, an additional list of sweet bodies. Some of the formulæ were arbitrarily doubled from the received fromulæ, and others fractionally reduced, for the sake, merely, of tracing this interesting relationship. The modification of the formulæ, and the list as then presented, were as follows: C1 H4O4 X3 Grape sugar. N Pb C4H2H Oз Sugar of lead. 3 = C4H2K 03 Acetate of potassa. C4H2H O3, H, O, Nitric ether, O3 X 1.5 Oxyd of glycerile. Br *Proceedings of the American Association for the Advancement of Science. Fourth meeting, held at New Haven, Conn., August, 1850. For the observation that this and the following four bodies may be included under this type, the author acknowledged his indebtedness to his assistant, Dr. Chas. H. Peirce. CI Several other compounds of sulphur with C, H, do not taste sweet. The following sweet bodies, one possessing a multiple and the other nearly a multiple of the number of atoms in glycocoll, do not readily admit of being written in the above formulaC10H110324= Valerianic acid. C16H1107 7= 34 Orcine. In reply to the inquiry as to whether sweetness may be ascribed to a peculiarity of form, the following facts are of sig nificance: C4H4S4 tastes sweet, and contains C, H and S. C4H4O4 66 *This body has a pleasant ethereal smell. The correspondence in constitution of this body with the next in succession gives additional interest to the formula. The taste is, therefore, not dependent upon any one of the elements present, since each may be replaced entirely by another without destroying the taste. In the communication submitted to the American Academy, attention was directed to the common formula, in which, according to Davy and to most modern chemists, all the acids containing hydrogen may be written, and also the oxygen acids which ordinarily exist in combination with an atom of water, as sulphuric and nitric acids; to wit, H + x; in which x represents all that part of the acid not replaced by metal in neutralization. A few examples follow: H+ClHydrochloric acid. H+ NOG Nitric acid. H+Cy Hydrocyanic" HSO3 Sulphurous HSO4 Sulphuric Butyric The inquiry naturally arises, have sour bodies a common form? to which, and not to the nature of the constituent particles, the property of sourness is to be attributed. They (the acids) are composed of one larger atom, or group of atoms united to the least atom, hydrogen, easily replaceable by a metal, and bound to the group by an affinity apparently much feebler than that of any of the remaining elements. An allusion was made, in the communication to the Academy, to the class of resins-some of the soluble members of which possessing a bitter taste-might, according to a research of Heldt upon Santonine, be referred to a single fundamental type. He refers the resins, for their origin, to the oxydation of the essential oils, and though the conception has been entertained by other chemists, it has first met with a full exposition in this paper. The hydrogen of essential oils oxydates, as a general thing, much more readily than the carbou. The following formula present Heldt's view of the production of resins. All are derived, he conceives, from C..H. These formula present in the original essential oils, groups of atoms, in which a part of the hydrogen occupies a more exposed. situation, if one may employ the illustration, than other parts of the molecule, and oxydates more readily. In this respect there is approximation to a common form, in view of which the in quiry was suggested, may the bitterness be ascribed to this form? This, however, does not furnish an explanation of the remarkable bitterness of the organic bases. Guided by the above suggestion, Prof. H. remarked, let the conception be entertained that the alkaloids have been derived from the greater or less oxydation of bodies having the general constitution of the essential oils, and the replacement of three atoms of water with one atom of ammonia for every atom of nitrogen contained in the organic base. The corresponding replacement of ammonia with three atoms of water is not of unfrequent occurrence in organic chemistry. Upon the speculation that this has been the derivation of the alkaloids, it will be easy to convert them into the essential oils from which they were derived. If we halve the formula of the oil, the first of Heldt's formulæ gives (C5H4)-Hx+0x=R. A certain number of atoms of hydrogen deducted from, and an equal number of atoms of oxygen added to, n times C&H constitute the resin. If, in adding nitrogen, we deduct for each atom of nitrogen three atoms of oxygen, or, which is the same thing, for each atom of ammonia (NH) added, deduct three atoms of water, we have an organic body containing C, H, N and O, a body corresponding in constitution with an alkaloid. By reversing this process, we may convert the alkaloid into its corresponding essential oil. Take for example Papaverin, one of the alkaloids of opium, analyzed by Merck, C40H21 NO 3.* Three atoms of oxygen for the atom of nitrogen, united to the eight atoms of oxygen, making eleven in all, correspond with eleven atoms of hydrogen, which, added to the twenty-one present, make thirty-two. C40 H21NO8-N-08+H8+03-C40H29+03, which correspond with C40H32 (CH4). There is doubt still resting upon the constitution of most of the alkaloids. Of those considered as best established, the following examples will be sufficient for a practical illustration of the above speculation. Thebain C25H14NO3 C25 H20=(CsH4)5. - The formula (CH 4 )0 − Hx + Ox + Oy =R, is suited to the derivation of Bebeerin. C35H20NO6=C35 H29=(C5 H4)7+H. * Liebig's Ann., lxvi, 125; Pharm. Contr., 1848, 930. Harmalin requires the addition of C2H2 to the second of Heldt's formulæ (CSHA)-Hx+Oy=R. C27H14N202 C27H22=(C5H4) 5+C2H2. Chinin and Cinchonin require the subtraction of C2. Strichnin requires the deduction of an atom of carbonic acid, or its equivalent CH2, and the same formula of resin as that of Bebeerin. C44H24N2O4 C44H34 (C5 H4)9 - CH2. Cotarnin requires the addition of an atom of carbonic acid. The following require slight modifications. Morphin C34H 19 NO6C34H28 (C5H4)7-C. Piperin C34 H19NO6|| C34H28 (C5H4)7-C. Veratrin C34H22NO6 C34H31 (C5H4)7—C+H3. It will readily be seen that in this series the differences between the essential oil and its derivative are such as would disappear with the addition or subtraction of an atom of carbonic acid, or water in some cases, and a little more or less oxydation in others. In those bases where the quantity of nitrogen is much larger, the third formula of Heldt would still give us the corresponding resins. (Cs H4)- Hx+0x+0y=R. Take for example Caffein. C14H8N404. The nearest essential oil of the constitution (C5 H 4 )" is C 15 H 12. C15H12-H4+O4+014+4(H3N) - 12HO=C15 H8N4O6. If we deduct from this formula an atom of carbonic acid, we have C15H8N4O6-CO2 C14H9N4O4. Theobromin differs, as has been remarked, from Caffein only by CH2. C14H8N4O4+C2H2=C16H10N404. The construction from the class of oils, above referred to, of the formula of those alkaloids in which the quantity of hydrogen is much greater, is more difficult. The foregoing relationships have an interest taken in connection with the inquiry to which attention has been directed, to wit, May there be a common form among bodies having a common taste? * Ann. Ch. Phys. [3] xix, 363; Ann. d. Ch. u. Phar., lxii, 95. Ann. Ch. Phys. [3] xix, 365. Ann. Ch. Phys. [3] xix, 370. Ann. Ch. Phys. [3] xix, 361; Ann. d. Ch. u. Phar., lxiii, 98. Ann. Ch. Phys. [3] xix, 363. Ann. d. Ch. u. Pharm., lxi, 338? Pharm. Cont. Blatt., 1847, 424. |