Imágenes de páginas
PDF
EPUB

ART. VIII.—Glycocoll (Gelatine Sugar) and some of its Pro

ducts of Decomposition; by Prof. É. N. HORSFORD.

(Continued from Vol.iii, p. 381.)

COMPOUNDS of glycocoll and sulphuric acid are even more remarkable than those with hydrochloric acid. As little success attended the effort to ascertain the precise conditions under which some of them are formed, as rewarded the labors with the compounds already described. Of these, two, the double sulphate of glycocoll and oxyd of ammonium, and the anhydrous sulphate of glycocoll, have especial interest, as they throw much light over the constitution and nature of this body. Anhydrous Sulphate of Glycocoll.

Gl, S0.. By dissolving glycocoll in hot spirits of wine, cooling, adding sulphuric acid drop by drop, and setting aside in a quiet place, after a day or two there are formed beautiful elongated thin flat prisms with right angled terminal planes. From another portion the salt crystallized in the most delicate attenuated tables of the greatest brilliancy. It is soluble in water and hot diluted alcohol, and quite insoluble in absolute alcohol and ether. It tastes sour and reddens litmus paper, does not change upon exposure to the air, and loses no weight by 100° C. (212° F.) Combustion with chromate of lead gave the following results:

I. 0:5147 grm. gave 0:4257 carbonic acid and 0-2509 water. II. 0:3134 0.2574

0.1616 III. 0.1541

0.1260 IV. 0:3397

0-7039 platin-salammoniac. V. 0:4248

with chlorid of barium 0.4673 grm. sulphate of baryta. In per cent. expressed agreeing with,

I.
II.

III.
Carbon, 22:55 22:40 22:30
Hydrogen, 5:41 5.72
Nitrogen,

13-05
Sulphuric acid,
Which give the formula

C, H, NO,, SO, as the comparison of estimated and analytical results shows.

Theory Experiment. Carbon,

4 equiv.
24 22.66

22 42 Hydrogen,

4

3.77

5:56 Nitrogen,

14 13.20

13:05 Oxygen,

3
24 22 64

21.00 Sulphuric acid,

1

37.73

37.97 106 100.00

100 00

(

[ocr errors]

IV.

V.

.

37.97

4

40

Repeated combustions did not enable us to lessen the per-centage of hydrogen. The variation from the theory is, doubtless, to be attributed to the absorption in the chlorid of calcium tube, of a small quantity of sulphurous acid, which escaped from the combustion tube. This explanation unfortunately occurred after repeated analyses had corsumed the stock of salt.

This constitution is remarkable in the field of organic chemistry. On its borders we have a similar instance in anhydrous sulphate of ammonia, NH, +50g.

Sulphate of Hydrate of Glycocoll.

GI, SO,,HO. This salt was obtained from a solution similarly prepared to that which yielded the anhydrous salt, except that the solution was boiled with sulphuric acid, instead of the latter being added to the cold solution. It crystallizes in short prisms, reminding one of sulphate of copper, and the crystals, though small, are of exceeding beauty and perfection of form. They do not change upon exposure to the air.

A single determination only was made, and that of the nitrogen. The other determinations were not made, from want of substance, all subsequent efforts to form the salt having failed. By Varrentrapp and Will's method :

0.3367 grm. gave 0-2943 grm. platin-salammoniac. In per cent. expressed, Nitrogen 12:37. This corresponds with the formula

C, H, NO,, SO,, HO, which requires 12:17 per cent. of nitrogen.

Basic Sulphate of Glycocoll.

(a.) 3G1 HO, 280., 2HO. If to a solution of glycocoll in diluted spirits of wine, sulphuric acid in excess be added, and set aside, in twenty-four hours long rectangular prismatic crystals form upon the bottom of the containing vessel. A very considerable excess of sulphuric acid did not change the constitution of the crystals.

They taste and react acid, and like the salts already described suffer nothing from exposure to the air.

Combustion with chromate of lead gave the following results:
I. 0:4199 grm. gave 0.3528 carbonic acid and 0-2149 water.
II. 0-3944
0:3219

66 0.1974 III. 0.2399

by Varrentrapp and Will's method, 0:5067 grm. platin-salammoniac. IV. 0:6866 grm. gave 0:4928 sulphate of baryta. V. 0.5808

0.4170 VI. 0-4532

0:3225 VII. 0.4960

0:3500

66

II.

III.

VI.

VII.

In per cent. expressed the above determinations correspond with I.

IV.

V.
Carbon, 22.91 22:25
Hydrogen, 5.68 5:56
Nitrogen,

13:31 Sulphuric acid,

24.62 24.62 24 20 24.40

24-62 These numbers give the formula,

3C, H, NO,, HO)+2(S0,, HO). The juxtaposition of the estimated per cents. and analytical results follows:

[blocks in formation]

The following formula is submitted as expressing the rational constitution of this salt :

(GI HO, SO, HOGI HO)+(GI HO, SO, HO). The following sulphuric acid compounds were none of them completely analyzed. They were prepared in small portions while seeking to obtain a neutral sulphate of hydrate of glycocoll; and it was not until the capacity of this body to combine with others of such different nature, and in such varied proportions became fully apparent, that the existence of so complex and unusual compounds was believed.

The crystallized salts were for the most part groups of elongated prisms.

Basic Sulphate of Glycocoll.

(b.) 3G1, 250, HO. The constitution of this salt differs from that of the preceding in the amount of water. As both of them were dried in the air over sulphuric acid, and suffered no change, this difference is attributable doubtless to the degree of concentration, or difference of temperature. It will be observed that it corresponds precisely with a basic hydrochlorate (d), whose constitution is given on page 380 of the last volume.

With chlorid of barium, 0.2182 grm. of crystals, gave 0-1940 grm. sulphate of baryta.

In per cent. sulphuric acid 27:74.
This corresponds with the formula

3(C, H, NO,)+280, +HO, which requires 27.87 parts in 100. As the probable rational constitution of this salt the following is submitted :

(GI, SO, +GI, HO)+GI, SO2.

Basic Sulphate of Glycocoll.

(c.) 3(Gl, HP) 250, HO. A mixture of the salt (b) with the previously described one (a), doubtless gave the crystals for the following determination :

0-3076 grm. gave 0·2300 grm. sulphate of baryta, which gives in per cent. expressed, sulphuric acid 25.65; corresponding with the above formula. The following is more rational.

(Gl, so, H0+Gl, H0)+(Gl, H0+50, HO). This requires 25:47 parts of sulphuric acid in 100.

(d.) 2(Gl, H0)+S0.. Another salt gave by combustion with chromate of lead,

From 0-3039 grm., 0·2872 grm. carbonic acid, and 0.1680 grm. water; which expressed in per cent., give carbon 25-77, hydrogen 6:01. These numbers correspond with the formula

2/C, H, NO,, HO)+SO,, which requires carbon 25.26, and hydrogen 5.26. Glycocoll and Sulphate of Oxyd of Ethyl.

GI, HO, AeO, SO. The particular circumstances of the formation of this salt, beyond those already given, viz. a solution in hot spirits of wine, or in water to which absolute alcohol was added, are not ascertained.

With chlorid of barium, 0:6470 grm. gave 0·3036 grm. sulphate of baryta; which in per cent. give of sulphuric acid 17-27. This quantity of acid corresponds with the formula

C, H, NO,, H0+C, H, O, SO,, which requires 17:62 per cent. of sulphuric acid.

Nitrate of Glycocoll.

GI, HO +NO, HO. The capability which this compound possesses of uniting with bases enveloped the earlier conceptions of the nature of glycocoll in obscurity an obscurity from which the changes the nitrate of copper salt experienced upon subjection to heat, and the simple combinations with the oxyds of silver, copper and lead, did not in any degree relieve it. It was then suggested that the glycocoll played the part of the water of crystallization in the salts that were formed. From the analysis below, it will be seen that the salts were double salts, in which glycocoll with or without water, as a base, united with hydrated nitric acid, or as a salt with nitrates of metallic oxyds.

Braconnot obtained this compound by direct combination of nitric acid with glycocoll prepared from isinglass. Dessaigne procured it directly from hippuric acid, employing nitric instead of hydrochloric acid for its decomposition.

We prepared it by dissolving glycocoll in strong nitric acid, and setting the solution over sulphuric acid to crystallize. Occasionally large tabular crystals, apparently belonging to the monoclinate system, are formed. Not unfrequently, however, the salt crystallizes in needles, especially if the fluid has been warmed.

They do not deliquesce upon exposure to the air. They taste and react acid. They were dried over sulphuric acid. Combustion with chromate of lead gave the following results :

I. 0:4509 grm. substance gave 0.2954 grm. carbonic acid, and 0.1963

grin. water. II. 0·4968 grm. substance gave 0.3122 grm. carbonic acid and 0.2054 grm. water.

Two analyses, according to l'arrentrapp and Will's method, gave respectively 10:04 per cent. and 10:64 per cent. of nitrogen. From this it is evident that this method cannot here be employed :-a fact with regard to nitrates, to which attention has already been drawn by the chemists just mentioned.

Failing in this, a determination was made by the quantitative method of Prof. v. Liebig.

The proportions of carbonic acid to nitrogen in four tubes, were: 17:9, 14:7, 10:5, 24:11; or, together 65:32=2:1. In per cent. expressed the above determinations give

I.

II.
Carbon,

17.86 17:15
Hydrogen,

4.83 4.59 Nitrogen,

20.50 These correspond with the formula

C, H, NO,, HO+NO, HO, as will be seen by the annexed estimates and results of analysis.

III.

[blocks in formation]

Boussingault by drying the salt at 110° C. (230° F.) obtained as already noticed the anhydrous compound C, H, NO, NO,.

Oxalate of Glycocoll.

Gl, 0, HO. An aqueous solution of glycocoll with oxalic acid, evaporated upon a watch glass, crystallizes in rays reminding one of a cross section of wavellite. if alcohol be added to a solution of glycocoll in oxalic acid, the latter in excess, the solution becomes milky, with the separation of oxalate of glycocoll. If added in small quantities and successively, it crystallizes with the beauty

« AnteriorContinuar »