TREPONEMA TA 587 
Add to Tube 1, 0.2 cc. of spinal fluid and mix thoroughly. With- 
draw exactly 1 cc. of the mixture and add to it Tube 2; repeat through 
the entire row, discarding 1 cc. from the tenth tube after mixing. 
Tube 11 contains 1 cc. saline only and serves as a control. The dilu- 
tions of spinal fluid run from 1 to 10 in Tube Xo. 1 to 1 to 5120. Add 
to each tube (Xo. 1 to Xo. 11 inclusive) 5 cc. of the colloidal-gold 
solution' and allow to stand twelve to eighteen hours at room tempera- 
ture. Tube 11 (the control) should be perfectly clear and of the color 
of the colloidal-gold solution. 
The colors are recorded as follows: 
1. (^hange to a faintly blue tint, red predominating. 
2. Change to a faint lilac tint, red less conspicuous. 
3. Change to a distinct blue tint, red practically gone. 
. 4. Change to a pale blue tint, no suggestion of red. 
5. Change to a practically colorless solution. 
Significance: In cases of general paresis, the color changes in tubes 
1 to 4 or 5 (1 to 10 to 1 to 80 or 1 to 160), are clearly marked. The 
maximum tendency toward decolorization and precipitation is usually 
in tubes of dilutions 1 to 40 or 1 to 80. In cerebrospinal lues the tend- 
ency toward a maximum reaction is in the higher dilutions, from 1 to 
160 to 1 to 820, but the diagnostic value is distinctly less than that for 
the paretic cases. Inflammations of the cerebrospinal axis may cause 
precipitation from 1 to (540 to 1 to 1280; tuberculous meningitis from 
1 to 160 to 1 to 320 (as for cerebrospinal lues). Xormal sera usually 
cause precipitation in the higher dilutions— up to 1 to 5000. 
The test, properly carried out, appears to be the most sensitive and 
reliable of any which have been tried up to the present time. 
Preparation of CoUoidal-goId Sohition for Lange Test. In prepar- 
ing the colloidal-gold solution, two factors are absolutely imperati\'e: 
First, all glassware must be chemically clean and exactly neutral in 
reaction. Second, all water must be distilled, first from dilute sul- 
phuric acid (5 cc. to 2 liters), then from Ba (OH)., solution (20 cc. to 
2 liters). The water must be condensed in a block-tin condenser tube 
and collected with as little exposure to the air as is possible. Such 
water is "conductivity" water, almost neutral in reaction (pn = 6.7 
approximately). Collect the middle third distilled water each time. 
Solvtions. — l. Gold chloride. Dissolve 1 gram Merck's C. P. gold 
chloride in 100 cc. conductivity water. 
2. Potassium carbonate. Dissolve 2 grams C. P. potassium car- 
bonate in 100 cc. conductivity water. 
3. Formaldehyde solution. Add 2.5 cc. neutral formalin (40 per 
cent approximately) in 100 cc. conductivity water. 
Colloidal-gold Sohdion.—I'lace 1000 cc. of conductivity water in 
a 2-liter Pyrex flask. Add 10 cc. of the gold-chloride solution (1) 
and 7 cc. of the potassium carbonate solution (2). Heat rapidly 
' See below for nreuuiiition. 
