Alfred Isaac Cohn.

Indicators and test-papers; their source, preparation, application, and test for sensitiveness . . online

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the Cc. of alkali used from that used in the boric-
acid titration.

If any ammonium salt is present, it is best to add
excess of caustic soda, drive off the ammonia by
boiling, and then add excess of acid.

With calcium borate, 2.5 Cm. are warmed with
I Cc. of concentrated hydrochloric acid, and the
process carried out as before.

If alumina is present, it should be precipitated
with ammonia, the ammonia liberated and driven
off by boiling, and the determination proceeded
with as before.

The author states that the indicator reaction is
very sensitive with decinormal alkali or acid, one
drop of either sufficing to effect an immediate color
change.



PATENT BLUE L. 235

PATENT BLUE L.

ALKALIES = Blue ACIDS = Green

Properties: Patent Blue L. is one of the class of tri-
phenylmethane dyes, and is supplied by the Roche-
ster Farbwerken. It is neutral in reaction and sol-
uble in water. The neutral and alkaline solutions
are blue in color; a slight excess of acid, however,
changes this to green.

Application: Patent Blue L. is recommended as an
indicator for estimating the excess of soda in bleach-
ing fluids prepared from chlorinated lime and sodi-
um carbonate. One drop of a i-per-cent solution
is added to the hypochlorite solution ; the latter is
then somewhat diluted, and titrated with normal
acid in the customary manner. Other indicators,
like methyl orange or litmus, are decomposed by so-
lutions containing chlorine, but this indicator is not.

PEREZOL

C, 6 H 19 (OH).0 8
ALKALIES = Pink to Mauve Rose ACIDS = Colorless

Synonyms: Pipitzahoic Acid; Pipitzahoinic Acid;
. Perezone ; Von Duyk's Indicator.

Source: Perezol is obtained from Pcresia adnata, A.
Gray (and various other species cf Ferezia), Com-
posite found in Mexico where they are known un-



236 INDICA TORS

der the name of " pipitzahoac." The cylindrical
rhizomes of the plant are about 20 Cm. long and 3
to 4 Mm. thick, and when dry are brownish exter-
nally, whitish-yellowish internally, and very fragile.
The fracture is fibrous. Between the medulla and
the cortical layer is a zone containing many orange-
yellow specks, and in which the perezol is localized.

Perezol was discovered by Profs. Altamirano and
Armendariz, of Mexico, by treating the coarsely
comminuted rhizome with benzene or toluene, and
evaporating the solvent at a temperature of about
50 C. The orange -yellow crystals are then recrys-
tallized. The yield is about 5 per cent.
Properties: Perezol, after recrystallization, forms
odorless, well- formed quadrangular prisms with
oblique terminals, and of orange-yellow color, and
a persistent acrid taste. Perezol melts at about 103
C., and sublimes at 110 C., yielding very deli-
cate, prismatic crystals practically insoluble in cold
water, but slightly soluble in hot water, and quite
readily soluble in alcohol, ether, benzene, toluene,
and oils, both fixed and volatile.

With bases, even ammonia and metallic oxides,
it yields violet-black salts. Acids added to an
aqueous solution of an alkali pipitzahoate precip-
itate the yellow pipitzahoic acid unchanged.
Treated with reducing agents, it yields hydroqui-
none hence the name " perezone " by which
it is also designated.



PEREZOL 237

Application: According to von Duyk, perezol is per-
fectly adapted for use as an indicator because of its
exceedingly great sensitiveness towards alkalies, the
faintest trace of which suffices to afford a pink to
mauve-red color. The end-reaction is, even with
ammonia, instantaneous, there being no transitional
stage, and is very sharp even in extreme dilutions.
Dissolved in distilled water, the solution is faintly
yellow ; on boiling, a red to mauve color develops,
due to the traces of alkali dissolved out from the
glass. One drop of perezol solution distinctly col-
ors water containing one drop of semi-decinormal
caustic-soda solution, or some aniline or pyridine.
Potable waters acquire a mauve-red color with
perezol, from the alkaline-earthy phosphates pres-
ent. Saliva also gives the reaction.

For use a I : 200 alcoholic solution is prepared,
one drop of which suffices. Perezol is suitable for
titrating alkaloids with which it reacts with great
delicacy. The indicator is not at all influenced by
heat. Solutions colored by alkalies are instantly
decolorized by free acids, even carbonic acid, as well
as mono- and poly-basic organic acids. The only ex-
ception is ortho-boric acid ; this acts like a base. If
glycerin be added to the solution, however, the
boric acid behaves like other acids.

The mineral salts of the strong acids, as well as
ammoniacal salts, are neutral towards the indicator ;



238 IN DIC A 7'OXS

acetates, bicarbonates, borates, and carbonates are
alkaline towards it.

Perezol is particularly adapted for estimating the
alkalinity, of potable waters, titrating alkaloidal res-
idues, borax and acetates, etc. It is moreover suit-
able for every kind of alkalimetric or acidimetric
determination. Its solubility in oils renders it,
besides, useful where ordinary indicators are not
available.



POTASSIUM FERROCYANIDE WITH
AMMONIUM MOLYBDATE



ATKATTFS- DeColori - Arm* Reddish -y ellow *> dark

ALKALIES- ACIDS - brown with excess



Application: A solution of the two salts is used as an
indicator in titrating acids (mineral, as well as phos-
phoric, sulphurous and arsenic). These afford a red-
dish-yellow reaction when present in very small
quantity ; with an excess of acid a dark-brown color
or turbidity is produced. On adding an alkali the
reddish-yellow or dark-brown color disappears.



SODIUM ALIZARINSULPHONATE 239

SODIUM ALIZARINSULPHONATE

C 14 H 7 O 4 SO 8 Na

Red ; with ex-
ALKALIES = cess> yiolet ACIDS =: Yellow

Synonym: Alizarin S.

Preparation: Sodium alizarinsulphonate is obtained
by the action of fuming sulphuric acid on alizarin,
and conversion of the alizarinsulphonic acid into a
sodium salt.

Properties: Sodium alizarinsulphonate occurs as an
orange-colored powder yielding an orange solution.
The solution of the indicator is rendered yellow
by acids. Alkalies in very slight excess change
the color to red ; a very large excess develops a
violet color.

Application: Sodium alizarinsulphonate serves for es-
timation of strong acids and bases. In the presence
of free phosphoric acid, as well as acid phosphates, the
indicator affords a yellow color; mono-phosphates
afford a red color, and basic phosphates a violet.
The color change from yellow to red during the
titration of phosphoric acid is quite sharp ; the
change from red to violet, however, is only very



240 2ND 1C A TORS

gradual, and appears to be due rather to the increas-
ing alkalinity than to the presence of neutral phos-
phates. The indicator has been used for estimating
the acidity of urine. The process is not, however,
very useful, since the color of the urine itself, as well
as the gradual color change, renders the observation
of the end-reaction uncertain.



INDEX



PAGl

Acetates, cochineal with 52

perezol with 238

Acid, acetic, Congo red with 56

fluorescein with ., 77

rosolic acid with 156

anchusic 25

arsenic, lacmoid with 99

methyl orange with 115

Poirrier blue with 136

arsenous, lacmoid with 98

methyl orange with 115

silver-nitrate paper with 214

phenolphtalein with 130

starch with 163

boric, curcuma paper with 186

iron salicylate with 233

phenolphtalein with 130

Poirrier blue with 136

carbonic, alkaline carmine solution with 45

carminic-acid with 48

alpha-napbtolbenzem with 30

cochineal with 52

curcumin with 62

curcumin W. with 63

Congo red with 56

flavescin with '. 75

fluorescein with 77

gallein with 82

241



242 INDEX

PAGE

Acid, carbonic, litmus with 104

luteol with 107

phenol nitrosylsulphonate with 126

phenolphtalein with 129

phenolphtalein paper with 206

potassium hydrorufigallate with 145

resazurin with 150

rosolic acid with *... 156

tropseolin OO with 169

tropseolin OOO with 172

tropseolin paper with 218

carminic 45

chromic, guaiac paper with 192

lacmoid paper with 194

silver-nitrate paper with 214

eupittonic 72

fuchsine-sulphurous 80

hydrochloric, huckleberry paper with 195

phloroglucin-vanillin paper with 206

potassium-sulphocyanate paper with... 211

hydrocyanic, ferrous-sulphate paper with 189

guaiac- and copper-sulphate paper with 192

Poirrier blue with 136

indigosulphonic 88

indigosulphuric 88

isopyrotritaric 230

nitric, brucine paper with 179

fuchsine with 180

lacmoid with 99

guaiac paper with 192

nitrophenylic 120

nitrous, potassium-iodide and starch paper with 210

phosphoric, cochineal with S3

curcuma paper with 186

lacmoid with 99

methyl orange with.. 115

potassium ferricyanide with 143

phyllocyanic - 133

pipitzahoic 235

rosolic, commercial 153



INDEX 243

PAGE

Acid, salicylic 157

salts, tropaeolin paper with 218

santalic 159

silicic, lacmoid with 99

sulphindigotic 88

sulphuric, in acetic acid, methyl violet for 119

Congo red with 56

sulphurous, alpha-naphtolbenzein with 30

brazilin with 41

fuchsine paper with 193

iodate paper with 197

starch with 164

yellow D 168

Acidity, corallin-malachite-green for 228

Acids, alkaline carmine solution with 45

alpha-naphtolbenzein with 30

benzopurpurine B, with 36

brazilin paper with 178

cochineal with 52

Congo red with 56

Congo-red paper with 184

fatty, curcuma paper with 187

methyl orange with 114

phenolphtalein with 131

fuchsine with 80

in alum, etc., ultramarine paper with 219

iodeosine with 92

iron salicylate with 233

lacmoid with 98

methyl orange with 114

mineral, alpha-naphtolbenzein with 30

flavescin with 75

hsematoxylin paper with 19 \

litmus with 103

methyl orange with 1 16

phenol nitrosylsulphonate with 126

organic, alpha-naphtolbenzei'n with 30

cochineal with 53

Congo red with 57

curcuma paper for 186



244 INDEX



Acids, organic, diazoparanitraniline-propylmetacresol with. 230

flavescin with 75

gallein with 82

lacmoid with 99

litmus with 105

methyl orange with 114

perezol with 237

phenacetolin with 124

phenol nitrosylsulphonate with 126

phenolphtalein with 131

tropaeolin paper with 218

perezol with 237

potassium ferrocyanide and ammonium molybdate

with 238

phenacetolin with 123

resazurin with 150

sodium alizarinsulphonate with 239

tropaeolin OO with 169

Albumin, citric-mercuric-chloride paper for 180

citro-potassium-ferrocyanide paper for 181

citro-sodium-tungstate paper for 181

picro-citric-acid paper with 207

potassio-mercuric-iodide paper with 208

Alcohols, Poirrier blue with 136

Aldehydes, fuchsine-sulphurous acid with 80

metaphenylenediamine hydrochloride for 133

Poirrier blue with 136

Alizarin 20

S 239

green B 225

green B. test-paper 226

green G 226

solution 25

violet 80

Alkali, corallin-malachite-green for 228

in soap, phenolphtalein for 131

Alkalies, alkaline carmine solution with 45

alkaline paper with 176

alpha-naphtolbenzem with 30

benzopurpurine B. with 37



INDEX 245



Alkalies, carminic acid with 48

cochineal with 52

curcuma paper with 186

diazoparanitraniline-propylmetacres 1 with 230

fuchsine with 80

gallein with 82

haematoxylin paper with 194

haematoxylon with 85

huckleberry paper with 195

iodeosine with 92, 94

iodeosine G. with 94

indigosulphonic acid with 88

iron salicylate with . .- 233

lacmoid with 98

litmus with 103, 104

perezol with 237

phenacetclin with 123, 124

phenol nitrosylsulphonate with ; 126

phenolphtalein with 129

Poirrier blue with 135

potassium bichromate with 140

potassium ferricyanide with 143

resazurin with 150

rosolic acid with 155

tannin paper with 217

Alkaline carmine solution 44

Alkaline earths, cochineal with 52

Alkaloids, ammoniacal copper sol tijn for 226

brazilin with 41

cochineal with 53

Congo red for 184

gallein with 82

haematoxylin with 85

iodeosine with 93

litmus with 105

methyl orange with 1 16

perezol with 237

phenolphtalein with 130

Alkanin 25

paper 176



246 INDEX

PACK

Alkanna red 25

Alpha-naphtolbenzem 29

solution of 30

Alpha-naphtol orange 171

yellow I 7I

Althaea paper 202

Alumina, lacmoid with 99

Aluminium salts, alizarin green with 226

Ammonia, alkanin paper with . . 176

benzoptirpurine B. with 36

benzopurpurin paper with 178

cochineal with 52

corallin with 58

curcuma paper with i85

curcumin with 62

curcumin W. with 63

diazoparanitraniline-propylmetacresol with 330

fuchsine with 80

fuchsine paper with 133

gallein with 83

hsematoxylin paper with 1 34

hasmatoxylon with 85

hyacinth paper with 195

huckleberry paper with 195

litmus with 104

luteol with 107

methyl orange with 115

orange-peel extract with 120

perezol with 237

phenacetolin with 123

phenol nitrosylsulphonate with 126

phenolphtalein with 129

phenolphtalein paper with 206

Poirrier blue with 135

potassium bichromate with 140

rosolic acid with 156

red cabbage with 42

Ammoniacal copper solution 226

Ammonio-ferric alum 94

Ammonium salts, alizarin green with 226



INDEX 247

PAGE

Ammonium salts, iron salicylate with 233

methyl orange with 114

perezol with 237

rosolic acid with 155

tannin paper with 217

tropseolin OOO with 172

Anchusic acid 25

Anchusin 25

paper 176

Aniline-azodimethylaniline 65

Aniline, Congo red with 56

Congo-red paper with 184

litmus with 105

methyl orange with 117

Aniline red 78

Anthocyanin paper 190

Anthracene violet 80

Arsenates, lacmoid with 98

litmus with 104

phenacetolin with 124

phenolphtalein with 130

Poirrier blue with 136

rosolic acid with 156

Arsenites, lacmoid paper with 199

litmus with 104

phenacetolin with 124

phenolphtalein with 130

rosolic acid with 156

Arsenfuretted hydrogen, corrosive-sublimate pap:r for 185

Atlas orange 170

Aurin 153

Aurin red 153

Autenrieth's indicator 106

Azaleine 78

Azolitmin 30

paper 177

solution 34

Azoresorcin 149

paper 211



248 INDEX

PACK

Barium hydrate with carbonate, phenacefcolin for 124

Bases, sodium alizarinsulphonate wkh 239

Benzaurin 34

Benzene-azodimethyl-aniline 65

Benzopurpurin B 35

paper 177

Beta-naphtol orange I/O

sulpho-azobenzene 170

Bicarbonates, carminic acid with 48

cochineal with 52

curcumin with 62

curcumin W. with 63

lacmoid with 98

methyl orange with 1 16

perezol with 238

phenacetolin with 124

Poirrier blue with 136

tropaeolin OO with 163

tropseolin paper with 218

Bichromates, Congo red with 57

lacmoid with 99

phenolphtalein with 130

Biphosphates, cochineal with 53

Congo red with 57

lacmoid with 98

Bismuth salts, potassium-iodide paper with 210

Bisulphites, Congo red with 57

lacmoid with 98

Blue carmine 89

Blue, Poirrier, C4B 135

Boas' paper 218

Boettger's indicator 54

ozone paper 217

paper 183, 191

Bolton's indicator 137

Borates, curcuma paper with 187

lacmoid with 98, 99

lacmoid paper with 199

litmus with 104

methyl orange with 116





INDEX 249



Berates, perezol with 238

Borax, curcuma paper with 186

curcumin with 62

lacmoid with 99

lacmoid paper with 98

perezol with 238

phenolphtalein with 130

Poirrier blue with 136

Borntrager's indicator 120

Brasilin 38

Brazilin 38

paper 178

Brazil-wood 37

test-solution 7

Bromeosine 68

Bromine, guaiac paper with 192

potassium-iodide and starch p:per with 210

Brucine paper 179

Buckthorn paper 179

Butter-yellow 65

Cabbage, red . . . . 41

tincture of 41

Calcium carbonate, mesitylene-quinone for in

Calcium hydrate with carbonate, phenacetolin for 123

Campeachy wood 85

Carbohydrates, Schiff's paper with 214

Carbon dioxide, diazoparanitraniline-propylmetacresol with. 230

monoxide, palladious-chloride paper with 205

Carbonates, alizarin green B. with 225

alkaline carmine solution with 44

alpha-naphtolbenzein with 29

cochineal with 52

curcuma paper with 186

diazoparanitraniline-propylmetacresol with 230

flavescin with 75

gallein with 82

haematoxylin with 85

indigo-sulphonic acid with 88

iron salicylate with , , 233



250 INDEX

PACK

Carbonates, lacmoid witH 98

lacmoid paper with 98, 199

litmus with 103, 104

methyl orange 1 16

perezol with 238

phenacetolin with 123

phenolphtalein with % . . . . 120

phenolphtalein paper with 206

Poirrier blue with 135

potassium hydrorufigallate with 144

rosolic acid with 155

Carmine 42

paper .....179

solution, alkaline 44

Carminic acid v 45

Caustic alkalies with flavescin 75

Cherry paper 191

Chloral, Poirrier blue with 136

Chlorides, Congo red with 57

lacmoid with 99

methyl orange with 114

phenacetolin with 124

rosolic acid with 155

Chlorine, brucine paper for 179

guaiac paper with 192

indigo carmine with 90

potassium-iodide and s.arch paper with 210

starch f or 164

Chromates, Congo red with 57

lacmoid with 99

lacmoid paper with 199

Chrysaurein 170

Cider, corallin-malachit.e-green with 228

Cobalt paper 182

Cobalt- and methylene-blue paper 182

Cochineal 49

paper 183

tincture, Luckow's 52

Cobaltous nitrate 48

Colein 54




INDEX 251



olein paper 183

Color-changes, sensitiveness of operator to 10

Common mallow 108

Congo red 55

paper 184

solution 57

Copper, ammoniacal solution 226

Corallin 58

red 58

solution 58

Corallin-malachite-green 227

Corrosive-sublimate paper 185

Citro-mercuric-chloride papers 180

molybdic-acid paper 180

picric-acid paper 207

potassium-ferrocyanide paper 181

sodium-tungstate paper 181

Cupric salts, potassium-ferrocyanide paper with 209

Curcuma paper 185

Curcumin 59

S 62

W . 62

Curcummin 59

Cyanides, ferrous-sulphate paper 189

Cyanine 63

reactions of, in acetic-acid solution 13

theoretically considered 16

Dahlia 118

paper ... 190

Dechan's indicator 80

Degener's indicator 122

Diamylcyanine iodide 63

Dianthine B 91

Dianthine G 93

Diazoparanitraniline-guaiacol 64

propylmetcresol 229

Diazoresorcin 149

paper 211

Diethylaniline orange 71



252 INDEX

PACK

Dieterich's table, showing sensitiveness of various test-papers 224

Dihydroxyanthraquinone 20

Diiodofluorescein-sodium 93

Dimethylamidoazobenzene 65

solution 66

Dimethylaniline orange in

Dimethyl-paraphenylenediamine paper 188

Dioxyanthraquinone 20

Dioxyphtalophenone 126

Diphenylamine 67

orange : 168

yellow 168

Direct violet 118

Diresorcin-phtalein 75

Elderberry paper 188

Engel and Ville's indicator 135

Eosine 68

solution 70

yellowish 68

Eosine-methylene blue 70

Erythrobenzeine 78

Erythrosin B 91

Erythrosin G 93

Ethane, palladious-chloride paper with 205

Ethyl orange 71

solution 72

Eupitton 72

Eupittonic acid 72

Extract orange-peel 120

Fast yellow 168

Ferment paper 189

Fernambuco 37

paper 178

Ferric salts, potassium-ferrocyanide paper with 209

potassium-sulphocyanate paper with 211

sodium salicylate with : 162

tannin paper with 217

Ferrous salts, ammonio-ferric alum with f . . . . 95



INDEX 253



Ferrous salts, potassium ferricyanide with 143

potassium-ferricyanide paper with 209

potassium permanganate with 147

Ferrous-sulphate paper 198

Fittig's indicator no

Flavescin 74

Fliickiger's sublimate paper 185

Fluorescein 75

solution 77

Formanek's indicator 225

Fuchsiacine 78

Fuchsine 78

paper 190

Fuchsine-sulphurous acid 80

Gallein 80

solution 82

Galvanometer, reflecting, as an indicator 147

Gawalowski's neutrality indicator 118

Gentian violet 3 B 1 18

Georgina paper 190

Geissler's test-papers 180

Glucose, indigo-carmine and sodium-carbonate papers with 196

Schiff's paper with 214

Gold-chloride paper 191

Gold orange in, 170

Greenwalt's paper 197

Guenzburg's paper 206

Griess's red test-paper 216

Griess's yellow test-paper 203

Guaiac paper 192

Guaiac- and copper-sulphate paper 192

Haematoxylin 82

Haematoxylon 85

paper 193

tincture 86

Harmaline 78

Helianthine in

paper 204



254 INDEX

PAGB

Herzberg's paper 184

Hexa-oxymethylaurin 72

Hoffmann's albumin paper 208

indicator 72

Hollyhock 108

paper 202

Houzeau's ozone paper 194

Huckleberry paper 195

Hyacinth paper 195

Hydrogen dioxide, dimethylparaphenylenediamine p per

with 188

potassium ferricyanide with 143

potassium permanganate with 147

tetra paper with 217

Hydrogen sulphide, alpha-naphtolbenzein with 30

brazilin with 41

cochineal with 52

Congo red with 56

dimethylparaphenylenediamine paper

with 188

lacmoid with 98

lacmoid paper with 199

lead paper with 200

litmus with 104

palladious-chloride paper with 205

tropaeolin OO with 169

Hypophosphites, potassium permanganate with 147

Hyposulphites, see Thiosulphates.

Illuminating gas, palladious-chloride paper with 205

Indicator, ammoniacal copper solution as an 226

Autenrieth's 106

Boettger's : 54

Bolton's 138

Borntrager's 120

Dechan's 83

definition of I

Degener's 122

Engel and Ville's 135

Fittig's no



INDEX 255



Indicator, Formanek's 225

Gawalowski's neutrally 118

Hoffmann's 72

Kruger's 75

Langbeck's 120

Luck's 126

Lunge's in, 122

Lux's 74

Oser and Kalmann's 144

Pellagri's 133

Richter's 138

Schaal's 20

Simon's 230

value of i

Von Duyck's 235

Von Miiller's i63

Weiske's 157

Weselsky's 149

Wolff's 232

Zaloziecki 29

Indicators, action cf in other than aqueous liquids 12

application of 8

artificial light with 10

characteristics of 3

classes of 3

correct choice of 5

deterioration of 9

dissociation of 15

general considera'kns of I

Mohr's theory of the action of 19

object of I

observing color-chrnges of 10

requirements of 2

see Table of Contents.

sensitiveness of to acids and alkalies, Tromms-

dorff's table, showing 220

sodium flame for 10

testing 9

theory of the action of 15

Indigo carmine 89



256 INDEX



Indigo-carmine paper 196

and sodium-carbonate papers 196

Indigo extract 89

paper 196

Indigosulphonic acid 88

Indigosulphuric acid 88

Indigotine 89

lodate paper 197

lodeosine 91

solution 92

lodeosine G 93

Iodine, guaiac paper with 192

Iodine, starch with 163

starch paper with 215

starch- and ammonium-persulphate paper with 216

potassium-iodide and starch paper with 210

zinc-iodide and starch paper with 219

zinc-iodide and starch solution with 173

Iris paper 197

Iron, isopyrotritarate 230

salicylate 232

Iron and ammonium sulphate 91

Japan wood 37

Jaune d'orient 93

Kroupa's parer 190

Kruger's indicator 75

Lacmoid 95

paper 198

solution 96

Lacmus 99

Langbeck's indicator 120

Lead paper 200

Lead salts, potassium-chromate paper with 208

potassium-iodide paper with 210

Lehman and Petri's dye 125

Litmus 99

paper 200



INDEX 257



Litmus paper, blue ........................................ 201

neutral .................................... 201

red ........................................ 201

solution ........................................... 102

tincture ........................................... 102

Logwood ................................................ 85

Luck's indicator ........................................... 126

Luckow's cochineal tincture ............................... 52

Lunge's indicator ...................................... in, .122

Luteol ................................. , ................. 106

solution ............................................ 108

Lutke's paper ............................................. 218

Lux's indicator ............................................ 74

Magenta ................................................. 78

Mallow ......... * ......................................... 108

paper ............................................. 202

Mandarin G. extra ..... .................................. . 170

Mandarin orange ........ . ................................. in

Manganous-acetate paper .................................. 203

Manganous-chloride paper ................................. 203

Mann's paper ............................................. 180

Mercuric-chloride pr.per ................................... 185

Merget's paper ............................................ ' 205

Mesitylene-quinone ....................................... no

Metadiamidobenzene ..................................... 132

Metallic salts, white-lead paper with ....................... 219

Metals, cobalt- and methylene-blue paper with ............. 182

Metaphenylenediamine ................................... 132

paper .............................. 203


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Online LibraryAlfred Isaac CohnIndicators and test-papers; their source, preparation, application, and test for sensitiveness . . → online text (page 13 of 14)