Part 11 (2/2)
Faint
Very
Very
- (Cr_{2}(SO_{4})_{3}.K_{2}SO_{4} M/10)
slow
slow
10 Ferric ammonium alum
-
Faint
+
Very (Fe_{2}(SO_{4})_{3}.(NH_{4})_{2}SO_{4}
slow M/10)
11 Ferric chloride
-
Fair
+
Slow (FeCl_{3} M/10-M/250)
12 Ferrous sulfate
-
Fair
-
+
Slow (FeSO_{4} M/10-M/6,250)
13 Copper sulfate
-
-
-
+
Very (CuSO_{4} M/5-M/125)
slow 14 Chromic acid
-
Bright
+
+ (CrO_{3} M/100)
15 Chromic sulfate
-
Faint
-
+
Slow (Cr_{2}(SO_{4})_{3} 2 per cent)
16 Chlorine water
-
-
+
+ 17 Bromine water
-
-
+
+ 18 Iodine in KI
-
-
+
+ 19 Sodium hypochlorite
Faint
Bright
+
++ (Cl water + NaOH)
flash
20 Sodium hypobromite
Faint
Bright
+
++ (NaOBr, bromine water + NaOH)
flash
21 Sodium hypoiodite
-
Faint
+
+ (I in KI + NaOH)
22 Calcium hypochlorite
-
Good
+
++ (Ca(OCl)_{2} saturated solution)
23 Turnip juice
-
Bright
-
+
++ 24 Turnip juice heated to 70
-
Faint
-
+
Very
slow 25 Turnip juice boiled
-
-
-
-
- 26 Alb.u.min solution
-
-
-
-
- 27 Alb.u.min solution + KMnO_{4}
-
Good
+
-
++ 28 Alb.u.min solution + KMnO_{4} boiled 1 min.
and filtered (no precipitate forms)
-
Good
+
-
++ 29 Gelatin solution
-
-
-
-
- 30 Gelatin solution + KMnO_{4}
-
Good
-
-
++ 31 Gelatin solution + KMnO_{4} boiled 1 min.
and filtered (no precipitate forms)
-
Good
+
-
++ 32 Colloidal Ag
-
Bright
+
+ 33 Colloidal Pt
-
Bright
+
+ 34 Colloidal Fe(OH)_{2} (dilute)
-
-
-
+
- 35 Sodium nucleoproteinate (liver)
-
-
-
+
- 36 Sodium nucleoproteinate (mammary gland)
-
-
-
-
- 37 Sodium nucleate (yeast)
-
-
-
-
- 38 Squid blood (Sepia esculenta).
Contains hemocyanin
-
Fair
++ 39 Squid blood (Sepia esculenta) boiled
-
Good
- 40 Lobster blood (Palinurus j.a.ponicus).
Contains hemocyanin and
tetronerythrin, a lipochrome
-
Faint
++ 41 Lobster blood (Palinurus j.a.ponicus)
boiled
-
Fair
- 42 Annelid blood (Laonome j.a.ponica).
Contains chlorocruorin
-
Good
43 Annelid blood (Laonome j.a.ponica) boiled
-
-
44 Luminous pennatulid extract
(Cavernularia haberi)
-
-
-
+
++ 45 Luminous ostracod extract
(Cypridina hilgendorfii)
-
-
+ 46 Luminous protozoan extract
(Noctiluca miliaris)
-
-
-
-
- 47 Firefly (Luciola viticollis) extract,
luminous organs
-
-
++ 48 Ferrous ferrocyanide (Fe_{2}Fe(CN)_{6})
-
Faint
+
+ 49 Zinc ferrocyanide (Zn_{2}Fe(CN)_{6})
-
-
+
Very
slow 50 Chromic oxide (Cr_{2}O_{3})
-
-
-
Slow 51 Chromic hydroxide (Cr(OH)_{2})
-
-
-
Slow
+ 52 Manganese dioxide (MnO_{2})
-
Good
Slow
Slow
++ ---------------------------------------------+------+------+-----+-----+-----
I believe the explanation of these phenomena lies rather in another direction and that the effect of the temperature and concentration of reacting substances affects not only the reaction velocity but also the reaction products. While intensity of luminescence undoubtedly increases with increasing reaction velocity, the luminescence itself probably accompanies only one stage in the formation of a series of oxidation products. This stage is favored at a definite temperature and ma.s.s of reacting substances. Thus, in the oxidation of phosphorus several intermediate oxides are said to be formed. The oxidation takes place in steps and probably the luminescence is connected with only one of the steps in a chain of reactions. It is probable that a certain oxygen pressure and temperature favors that particular step at the expense of the others and so this oxygen concentration and temperature correspond to the optimum for luminescence.
The supposition that certain definite oxidation products of pyrogallol must be formed in order to produce light is borne out by the fact that pyrogallol must be oxidized in a particular way to obtain luminescence.
The blackening of pyrogallol with absorption of oxygen in presence of alkali is a very well-known reaction, but luminescence does not accompany this type of oxidation. I have tried mixing all concentrations of pyrogallol and all concentrations of alkali in an endeavor to obtain some light, but always with negative results. Likewise my attempts to obtain light during the electrolysis of salt solutions containing pyrogallol by means of the nascent oxygen at various kinds of anodes have met with negative results. A similar case is presented by luciferin which oxidizes spontaneously (most rapidly in presence of alkali) without light production and only produces light when oxidized in presence of luciferase.
To sum up the results of the dynamics of chemiluminescence we may say that certain oxyluminescences occur only if the substance is oxidized in a particular way under definite conditions of temperature and concentration and that this is probably due to a favoring of one step (with which the luminescence is a.s.sociated) in a chain of oxidations.
Providing temperature and concentration are such as to favor the step responsible for luminescence, then higher temperature and greater concentration result in increased intensity of luminescence.
Let us now turn to luminous organisms and consider the effect of temperature and of concentration of reacting substances (oxygen, luciferin and luciferase) on the luminescence. We have already seen that luminescence of a luciferin-luciferase mixture begins with an extraordinarily low oxygen tension and increases in intensity with increasing tension of oxygen, but that very soon an oxygen tension is reached where a maximum luminescence is obtained and further increase of oxygen tension gives no brighter light. In this respect the luminescence intensity--oxygen tension curve is no doubt very similar to the haemoglobin saturation--oxygen tension curve. Haemoglobin is about 50 per cent. saturated at 10 mm. oxygen pressure, 80 per cent. saturated at 20 mm. oxygen pressure and completely saturated at pressures of oxygen well below the pressure of oxygen in air (152 mm. Hg). As the optimum oxygen tension for luminescence of luciferin is also well below that of air, mixtures of luciferin and luciferase luminesce with equal brilliancy whether air or pure oxygen is bubbled through them. To obtain an excess of oxygen it is only necessary to keep the solution saturated with air and statements regarding concentration of luciferin and luciferase and intensity or duration refer to excess of oxygen.
Investigators who have studied the effect of increase in oxygen pressure on luminous animals have come to the same conclusions. High pressures of air or oxygen do not increase the intensity of luminescence (Dubois and Regnard, 1884).
The hydrogen ion concentration of crude solutions of luciferin and luciferase, made by extracting whole Cypridinas with hot or cold water is fairly constant, about PH = 9, determined electrometrically. Such solutions have a high buffer value and the PH does not change during oxidation of luciferin so that this variable is automatically controlled.
Because of difficulties in measuring low intensities of light which are constantly changing, no figures on light intensities can be given, but it is easy to establish the following facts: The greater the concentration of luciferin or luciferase the more intense the luminescence. The greater the concentration of luciferin the longer the duration of luminescence and the greater the concentration of luciferase, the shorter the luminescence lasts. Thus, if we mix concentrated luciferin and weak luciferase we get a bright light which lasts for a half hour or more, gradually growing more dim. Concentrated luciferase and weak luciferin give a bright flash of light which disappears almost instantly. Concentrated luciferase and concentrated luciferin give a brilliant light which lasts for an intermediate length of time and weak luciferin and weak luciferase give a faint luminescence which lasts for an intermediate length of time.
These facts can all be explained by regarding luciferase as a catalyzer which accelerates the oxidation of luciferin and by a.s.suming that intensity of luminescence is dependent on reaction velocity, _i.e._, on rate of oxidation. Contrary to the condition for phosphorus and for pyrogallol there appears to be no optimum concentration of luciferase or luciferin, but the luminescence intensity increases gradually with increasing concentration of luminous substances up to the point where pure (?) luciferin and pure (?) luciferase, as secreted from the gland cells of the animal, come in contact with each other. This, the maximum brightness, is not to be compared with the light of an incandescent solid, but is nevertheless visible in a well-lighted room, out of direct sunlight.
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