CH,CH2ONO, and isobutyl nitrate, (CH3)2CH. CH2ONO2, are representatives of this class. -x 5. CH This glucophore is present in sweet compounds containing halogen bound to one carbon atom. The abbreviation H1 is general for chlorine, bromine, and iodine. Fluorine derivatives may be included possibly. The small index x refers to the number of halogen atoms in the glucophore. It may vary from one to three, the number of hydrogen atoms in the glucophore meanwhile decreasing from two to zero. An application of these principles is shown in the following two examples :

Methyl iodide has the glucophore CH2I- which agrees exactly with the general formula given. In this case, the I limits the abbreviation H1 to a single atom of halogen. The index x equals one. In respect to the hydrogen, the index 3-x becomes equal to two. Obviously, this represents the number of atoms of this element in the glucophore.

Chloroform has a glucophore, -CCl,, which agrees exactly, as before, with the general formula. In this particular case H1 stands for CI, the index becoming 3 for the chlorine. The H term in the formula completely disappears, a condition following logically from the simple assumptions made.

6. CH-CHY H2-y

This glucophore is also present in sweet compounds containing halogen. In strict agreement with the former

para

graph, the H1 is general for chlorine, bromine, iodine, and with doubt, fluorine. In respect to the indices, x may vary from one to three, and y from one to two. In consequence, the number of hydrogen atoms change at the same rate, but inversely. The following two examples will serve to make these relations clear :

Ethylene bromide has the glucophore CH,Br. CHBr-, which satisfies the formula, since Hl is equivalent to Br and x and y are each equal to unity.

Pentachloroethane has the glucophore CC, CC12-- Here H1 is represented by Cl, while r becomes equal to 3, y to two. Since the H term disappears, this glucophore contains no hydrogen.

7. While the 6 glucophores mentioned are undoubtedly the most important it is probable that this list may be expanded considerably. There are strong indications that the following groups, for instance, may be included in the list :-

(a) CO,H.CHNHCH,--,(H). Example: sarcosine, CH,NH.CH2.CO2H, which, according to Volhard (Ann., 1862, cxxiii., 262) has a sweetish

taste.

with different glucophores have been discussed already in the preceding paragraphs.

2.

CH,.-Several instances are cited already showing that this radical forms sweet compounds with glucophores, but we wish to point out that the halogen derivatives, especially, yield numerous examples of such combinations. Thus ethyl bromide and iodide are sweet, although the taste of the former is said by Fehling (Cohn, Loc. cit., p. 128) to be "burning" while the taste of the latter is not stated at all.

gluc are found in the literature, except in the case 3. CHCH2.-Examples supporting this auxoof glucophores containing halogens. We have been able to satisfy ourselves that it applies to those as well by tasting propyl bromide and propyl iodide. Both are sweetish as we expected.

com

4. CH.CH.CH,.-At present but few pounds containing this auxogluc are known to be vation. sweet. We include it in our list with due reser

5. (CH)CH.-Examples of combinations of this auxogluc with five of the six glucophoric groups are mentioned in the literature. The resulting substances are sweet with one notable exception. 3-Methylbutane-1,2-diol is said by F. Flawitzki (Ann., 1875, clxxix., 351) to be "burning bitter." An investigation of this compound is under way.

6. CH2OH.-This auxogluc yields with the different glucophores some of the most important sweetstuffs. Substances containing it will be cited from each class.

7. and 8. CH,CHOH- and CH2OH.CH,.—We have several instances to cite, especially in conjunction with the glucophores -CHNH2CO2H and CH2OH.CHOH-, which indicate strongly that these two radicals are really auxoglucs. The dl-a-amino-y-oxybutyric acid of Fischer and Blumenthal (Ber., 1907, xl., 110) as well as the a-amino-8-oxybutyric acid of W. Sternberg (Arch. f. Anat. Physiol., 1915, p. 226) are sweet. 1,2,3-Butanetriol and 1,2,4-butanetriol are other examples. The list, however, is far from being complete in this instance and much work has yet to be done in order to prove that these two radicals may actually be included in the list.

9. Finally, the radicals CnH2n+On of normal polyhydric alcohols seem to act as auxogluc's without exception. The fact that sugars and polyhydric alcohols are sweet need hardly be mentioned. The d-glucosaminic acid of Fischer and Tiemann (Ber., 1894, xxvii., 142) is a good example (C. Neuberg, Ber., 1903, xxxv., 4013), proving that this holds true for the glucophore CO,H.CHNH,− also.

Classification of the Auxoglucs.

glucs determined may be classified conveniently As will be seen from the foregoing, the auxo

under four heads :

instance, may probably be included. But it is not permissible to do this until more experimental data can be obtained. Hasty generalisations easily lead to wrong conclusions, especially in this field. Faulty or conflicting observations on the subject are pretty numerous and due largely to individual differences in the sense of taste. Besides we do | not yet know all the factors which tend to make compounds containing a glucophore taste bitter, and the source of notable exceptions.

The Influence of Acid Radicals.

We have just seen that all the saturated alkyl groups containing from one to three carbon atoms may act as auxoglucs. All of the higher paraffins do by no means act in the same way. Normal octyl iodide, for instance, is not sweet. Nor do all derivatives of the first members of the paraffin series act as auxoglucs. Glyceric acid, for instance, contains the glucophore CH2OH.CHOH—, yet the presence of the acid radical -CO2H not belonging itself to a glucophore, causes the resulting compound to taste sour. The radicals of the lower fatty acids as well as the radicals of oxyacids yields, with a glucophore, acid compounds.

The Influence of the Phenyl Group.

As has been pointed out repeatedly by Cohn (Loc. cit.), the entrance of a phenyl radical tends to make an otherwise sweet compound bitter. Glycol is sweet, styrol is slightly bitter. There seem to exist quite a number of radicals which yield with a glucophore bitter compounds, but in view of the limited data on hand, we have to postpone the discussion of the rules governing this change of taste.

The Influence of Stereoisomerism. Some seeming exceptions to our rule are due to stereoisomerism.

Thus, Z-valin (CH,),CH.CHNH,CO,H, is made up of the glucophore -CHNH2.CO2H ́ and the auxogluc (CH,),CH- and might be expected to be sweet. According to E. Fischer (Ber., 1906, Xxxix., 2328), it is insipid and weakly bitter. However, the d-valin, and consequently the dl-valin too, are sweet.

. It follows, therefore, that the racemic a-amino acids, but not all the optically active a-amino acids fall within the scope of our theory.

Determination of the Taste of an Organic
Compound.

If then we wish to predict whether a given compound is sweet or not, we first will determine if it contains a glucophore. If not, we may conclude immediately that the substance is not sweet. But even if we find the substance under consideration to contain a glucophoric group, we have to determine further whether an auxogluc is present too, or if the substance contains perchance an acid radical. In the former case the substance will be sweet, in the latter sour. A few examples will make this clear.

Serin, CH,OH,CHNH,.CO,H, may be divided in two parts, CO2H.CHNH, and CH2OH—. The former we have seen to be a glucophore, the latter is an auxogluc. The compound made up of two such parts should be sweet, a conclusion which agrees with the facts.

1soserin, CH, NH,. CHOH.CO,H, although made up of the same atoms and "sapophores" (Cohn), does not contain the same glucophore from the standpoint of our theory, and consequently it should not be sweet. In the literature it is described as "insipid" (E. Fischer and W. E. Jacobs, Ibid., 1907, xl., 1057, 1064).

a-Aminobutyric acid, CH,CH,CHNH,CO,H, is made up of the glucophore, CO2H.CHNH, and the auxogluc, CH,CH,—, and consequently it is sweet. On the contrary aspartic acid, CO2H.CH,.CHNH, CO2H, while containing the same glucophore, is linked to an acid radical and it tastes

sour.

Acetylene tetrabromide is made up of the glucophoric group CHBг,. CBг,- and hydrogen as auxogluc. In accordance with our theory it should be sweet. A careful test convinced us that in alcoholic solution it tastes disagreeably sweetish.

1,2-Propanediol is sweetish. It contains the glucophore CH2OH.CHOH- and the auxogluc CH,-.

The monomethyl ether of glycol, CH2OH.glucophore, and it is described in the literature CH2OCH,, on the contrary, does not contain a as tasteless (M. H. Palonua, Ber., 1902, XXXV., 3300).

Finally, we select a member of the sugar group. Glucose is made up of the glucophore CH2OH.CO― and the auxogluc CH2OH(CHÓH),-, the latter corresponding to the general formula CnH2+;

10.

The tables following, not only will include the necessary literary references to the above examples, but to a great number of other substances of this kind in addition. It is true that some of the derivatives included in our list are said to be bitter or tasteless. We question, however, some of these statements and we have already found them in several instances to be based on inaccurate observation.

Limitations and Possibilities of Our Theory.

It was pointed out at the beginning of this article that we confined the application of our theory at first to the more important sweet aliphatic compounds. The numerous cases in which the theory was verified seem to justify its publication, although we are well aware that there exist apparently some notable exceptions to our rule.

We hope to extend the scope of our theory soon. The combination of two glucophores, for example, seem to be sweet in most cases, i.e., a glucophore may act probably as an auxogluc also.

This

We further intend to apply our theory, with certain modifications, not only to sweet aromatic compounds, such as the saccharine of Remsen, but also to bitter substances in general. study will require considerable time and work. We finally have the pleasure to thank Professor Dr. R. E. Swain for interest and encouragement kindly given us in connection with this study.

Taste Trials.

Methyl iodide, CH,I.-Prepared after Dumas and Peligot (Ann. 1835, xv., 30), by treating methyl alcohol with red phosphorus and iodine. B.p. 43°. Taste sweetish.

Taste. Sweet

C. Neuberg, Ibid., 1903, xxxv.,

4013.

Literature.

Millon, Ann., 1843, xlvii., 374.

G. Bertoni, Gazz. chim, ital., 1890, xx., 373
G. Bertoni, Ibid., 1890, xx., 373.

Cohn, Loc. cit., 1890, xx., 412.

A. Wurtz, Ann., 1855, xciii., 120.

W. Hofmann, Ibid., 1848, lxviii., 333.
Fehling, Handworterbuch der chemie, vi., 1273.
L. Henry, Ann. chim. phys., 1872, [4] xxvii.,

242.

ix., 648) from primary propyl alcohol, red sphorus, and iodine. B.p. 102°. Taste: etish. Taste develops tardily.

1-, 2,2-, Tetrabromoethane, CHBr.CHBг2.pared according to W. Muthmann (Kryst. #., 1899, xxx., 73), by treating acetylene (made m calcium carbide) with bromine. The raw duct was successively washed with water, lium carbonate, sodium thiosulphate, and with ter again. It was then extracted with ether, ed with calcium chloride, and the ether distilled

issification of Aliphatic Sweetstuffs According

to Glucophores and Auxoglucs.

In our new classification of aliphatic sweetfis, the substances are first sub-divided in ferent classes, according to their glucophores. us all substances that owe their sweet taste to : glucophore CH2OH.CHOH- are to be found Table I. Within each table the sweetstuffs : arranged according to their auxoglucs. In order to locate a given sweet compound, ermine first its glucophore and its auxogluc by : method previously described. Then examine ts for the corresponding glucophore and auxoic, the latter to be found in the first column of ch table.

If the substance be sweet and there is no space it in the table, its taste is not yet known, as as we can ascertain; or it does not fall within present scope of our theory.

THE Imperial Mineral Resources Bureau in a pamphlet entitled "The Mineral Industry of the British Empire and Foreign Countries," gives statistical and technical information concerning the mining or quarrying of minerals during the period 1913-1919.

Fuller's Earth.

In a short paragraph giving the general properties, nature, &c., of Fuller's Earth, the mineral is described as a clay-like material, usually nonplastic and of a greyish, yellowish, greenish or bluish colour. Its chemical composition is essentially a complex aluminium silicate, with variable amounts of iron oxide, magnesia, lime and alkalies.

Its uses include:-as a filler for paper; as a carrier for certain pigments; as an ingredient for some soaps; its chief uses being for the removal of grease from woollen goods and for the decolorisation and clarification of oils.

The chief sources of supplies are England and the United States of America. Table I. gives the production in the United Kingdom.

1913

1914

1915

640

630

3,559 27,410

4,256 32,976

4,425

5,577

4,109 23,807

3,783

3,469