Lange's solu'tion

(lahng'eh) [0. Lange, German biochemist, contemporary.] Colloidal gold solution: to 500 c.c. hot distilled water add 5 c.c. of a 1 per cent, solution of gold chloride and 5 c.c. of a 2 per. cent, solution of pota ium carbonate, and then heat rapidly to the boiling point; then add CO. of a I per cent, dilution of formalin and shake until the solution is of a clear red color. L.'s test, gold sol test, to determine the presence of reducing bodies in the spinal fluid:! 12 test-tubes are prepared containing from i—10 to 1—20,000 dilution of spinal fluid in 0.4 per cent, sodium chloride solution; to each of the tubes 5 c.c. of L.'s solution is added and allowed to stand 24 hours; the gold is precipitated to a varying extent in the different dilutions, the greatest precipitation in syphilitic and para syphilitic cases being in the i-io dilution.