Sidebilder
PDF
ePub

-48

[ocr errors]
[ocr errors]

}

52

C =

Echicerin, C30 H143 0.2. Dextro-rotatory. Ether. d = 0·73. c = 2. t = 15. [a], 63.75. Jobst and Hesse (L. A. Chloroform. 2. t = 15. [a], 65.75.

178, 49). Echitin, C32 H,2 02 Dextro-rotatory.

. Ether. 2. t = 15°. [a],

72:7.? Jobst and Hesse (loc. cit). Chloroform. c = 2. 15°. [a]o

75.3.)
Echitein, C., H, 0. Dextro-rotatory.

C42
Ether. c = 2. t = 15°. [a], 88.

Jobst and Hesse (loc. cit).
Chloroform. c = 2. t

15°. [a]

85.5) Echiretin, C35 H56 02. Dextro-rotatory. Ether. c = 2. t = 15°. [a], = 54.8. Jobst and Hesse (loc. cit).

t =

[ocr errors]

$ 122. Bile Constituents.

Cholesterin, C26 H144 0, or C25 H42 O. Lævo-rotatory.

From gall stones. Anhydrous substance.
Ether. d = 0·72. C = 2. t = 15. [a]p 31.12.
Chloroforn.
c = 2 to 8. t 15. [a],

(36.61 + 0.249 c).
Hesse (L. A. 192, 178).

Lindenmeyer (J. für prakt. Chem. [1] 90, 323), examined by Broch’s method solutions of cholesterin (with 1 mol. water?) in rock-oil, c= 10, and in ether, c = 7.941, and obtained the follow

c ing specific rotations :

[blocks in formation]

Phytosterin, C26 H440. Lævo-rotatory. From calabar beans or seed peas. Chloroform. c = 1.636. t = 15°. [a], 34•2. Hesse (L. A. 192, 177).

The following determinations of specific rotation of bile acids were made by Hoppe-Seyler (J. für prakt. Chem. [1], 89, 257) by Broch's method, employing sunlight.

Glycocholic acid, C26H43 NOg. Dextro-rotatory.

From ox bile. Alcoholic solution. c= 9.504. The concentration of the solution is without influence.

Lines

[a]

C. + 21.6

D 29.0

E 37.9

b 40.0

F 48.7

G 56.8.

samt

26

=

5

5

Glycocholate of soda, C2H42 Na N0g. Dextro-rotatory. . Alcohol. c = 20.143. [a]] 25.7. Concentration without influence. Water. c = 24.928. [a] 20.8.

Taurocholate of soda, C26 H4 Na N S Oq. Dextro-rotatory. Alcohol. c = 9.898.

[a] 24:5. [a! 39.0. Concentration without influence. Water. C = 8.856.

[a])

21.5. [a] 34.0.
Cholalic acid, anhydrous. C24 H 4 Og. Dextro-rotatory.
From ox bile-

Alcohol. c = 3.338. [a]} = 50-2.
From dogs' excrement-

Alcohol. c = 2.942. [a]! 47.6. [a]; 50•4.
Cholalic acid, crystallized with water, C24 H40 0; + 21 H, 0.
Dextro-rotatory.

From ox bile or dogs' excrement. Alcoholic solution. ( = 2.962 (= 2 659 anhydrous substance).

Lines B с D E b F G H Hydrated :

25.3 27.0 30.4 40:1 42.2 47.3 60.8 70.1 Anhydrous: [a] 28.2 30:1 33.9 44.7 47.0 52:7 67.7 78.0

Other specimens of the crystallized compound gave the following rotations, calculated for the anhydrous acid :Alcohol. c = 4:43 anhydrous substance : [a]o = 34.8. - 6.0695

[a]e = 35.4. 2.7065

[a]; 35.2. 2.0298

[a]; 34.5. 1.8040

[a]; 34.2.
Cholalate of potash, C., H3, K 0. Dextro-rotatory.
C24

.
Solution in Alcohol, c = 22.
Lines с D E b F

[a] = 23.7 30.8 38.5 40.9 47.5.
Solution in water. c = 29.775. [a]o 24.9.

22.332. [a] 24.1.
c = 16.749. [a]] 24.6.

12.562. [a]p 25.9.
7.000. [a]

27.5.

6.004. [a]p = 28.2.
Cholalate of soda, C2, H3, Na Oz. Dextro-rotatory.
Alcohol. c = 2.2296. [a]” 31.4.
Solution in water. C = 19.049.
Lines B С D E

F
= 19.7

21.0 26.0 33.1 34.9 42.0. Decrease of concentration raises the specific rotation.

C =

C =

[ocr errors]
[ocr errors]

C =

39

C

[ocr errors]
[ocr errors]

C =

=

39

[ocr errors]

39

5

[ocr errors]

Cholalate of methyl, C24 Hz, (CH) 03. Dextro-rotatory. Alcohol. c = 4:59. [a]D

31.9.
Cholalate of ethyl, C24 H3, (C, H;) 03. Dextro-rotatory.
Solution in alcohol.

c = 18.479.
Lines B D E 6

[a] 25.4 32.4 40.5 42:3.

39

§ 123. Gelatinous Substances.

1.

All these substances, and particularly chondrin, possess strong lævo-rotatory powers. The following observations were all taken by de Bary (Hoppe-Seyler, Med. chem. Untersuchungen, 1, 71) :Glutin. Aqueous solutions.

c = 6:12. { t = 24° to 25°. [a]

It

35° to 40°. [u]

24° to 25°. [a] 3.06.

35o. [a]] The rotatory power of glutin solutions decreases with rise of temperature. Concentration, on the other hand, has no important influence.

The following experiments with aqueous solutions of concentration c = 3:06, show the effects of alkalies and acids :

140.0.
123.0.
130.5.
125.0.

t

2.

C=

1. Solution mixed with an equal vol. ammonia [a]o
2.

a few drops solution of soda [a],
3.
an equal vol. soda

[a]!
4.

an equal vol. acetic acid [a]p

[blocks in formation]

[ocr errors]

Chondrin. Pure aqueous solutions of sufficient transparency cannot be prepared, but the cloudiness disappears on the addition of a few drops of soda solution. For such a solution with c = 0.957, it was found that

[a]; 213.5. After the addition of an equal volume of soda solution.

{a] 552.0. The latter solution diluted by the addition of an equal volume of water

[a] 281.0.

=

§ 124. Albumins. All the albumins are lævo-rotatory. The following observations on their specific rotation are given by Hoppe-Seyler (Zeitsch, für Chem. u. Pharm. 1864, 737).

[ocr errors]
[ocr errors]
[ocr errors]

Serum-albumin. Neutral aqueous solution

[a] 56. Aqueous solution saturated with sodium chloride

[a]5 64. Aqueous solution saturated with addition of acetic acid

[a]]

71. Aqueous solution with addition of concentrated hydrochloric acid till the precipitate at first formed again disappears

[a]] = 78.7. Potash and soda solutions, by forming alkali-albuminate, cause a considerable increase of rotatory power, even when present only in small quantity. Prolonged action of the alkalies, particularly at higher temperatures, again reduces the amount of rotation.

Egg-albumin. Aqueous solution. Rotation independent of concentration [a]] 35.5. Aqueous solution after addition of hydrochloric acid

[a] - 37.7.

Casein.

[ocr errors]

91.

Dissolved in magnesium sulphate solution

[a]p

- So. Solution in dilute hydrochloric acid (4 cub. cent. of fuming acid per litre of water)

[u]

87. Solution in smallest possible quantity of soda solution

[a] 76. Albuminate (protein of Mulder), obtained by the action of concentrated potash upon albumins, always exhibits higher rotatory power than the latter. The following maxima have been observed :Albuminate from serum-albumin

[a] 86.
uncoagulated egg-albumin

[a] 47.
coagulated egg-2
- albumin

[a] 58.5. casein. Solution of casein in strong potash.

Rotation varies with strength and amount
of potash used

[a]] Paralbumin, from ovarian cysts. Examination of the natural feebly alkaline solutions gave in several observations :

[a]D 59, 61, Syntonin, obtained from myosin of muscles by solution in very dilute hydrochloric acid, or by the action of concentrated hydrochloric acid upon albumins (coagulated egg-albumin or fibrin). Solution in very dilute hydrochloric acid. Rotation independent of concentration [a]] = – 72.

. In weak alkaline solutions the substance exhibits very nearly the same amount of rotation. By heating the hydrochloric acid solutions in a closed vessel to 100°, the specific rotation rises to [a] = – 84:8.

64.

[ocr errors]

.

APPENDIX.

ON THE ESTIMATION OF MALTOSE AND DEXTRIN IN MALT WORTS

AND BEERS.

By J. STEINER, F.C.S.

When an infusion of malt in cold water reacts on soluble starch under certain definite conditions, a chemical change takes place, which has attracted the attention of chemists for a considerable time. This chemical reaction being, moreover, of great practical importance in brewing, for example, numerous experiments have been performed to explain it. The results arrived at, although differing widely in many respects, lead nevertheless to the conclusion, that the starch is converted by the action of cold malt extract (diastase) into maltose and dextrins. These compounds are the only products under the most favourable conditions of temperature (550 to 63° C.), if the diastatic action continues no longer than two to three hours. But a more prolonged contact of the diastase leads to the partial conversion of maltose into dextrose, while the gradual saccharification of some of the dextrins into maltose, and the formation of dextrins of simpler molecular compositions seem to proceed during the whole time of the diastatic action,

If starch be boiled with dilute sulphuric or hydrochloric acid, dextrins, maltose, and finally dextrose are produced, but if the action be too protracted, or the acid too concentrated, the so-called neutral carbo-hydrates are formed simultaneously. These latter are not capable of fermentation, nor of reducing alkaline solution of metallic salts, and have no rotatory power. The progress of the conversion may be watched by an iodine solution, which gives the following colour reactions. First, a deep-blue (soluble starch); secondly, a violet (amylo-dextrin); thirdly, a red (erythro-dextrin); and finally, no change of colour (achro-dextrin, maltose and dextrose.)

« ForrigeFortsett »