11 
abstracts of all of these within the scope of this article. In general 
it may be said that these investigations have been concerned with 
improvements in the general technique of the test, with the use of 
various chromogenic substances in the place of guaiacum, with the 
stud}^ of the conduct of various substances other than blood toward 
such reagents, and with the delicacy of such tests. Finally, a num- 
ber of these communications are devoted in whole or in part to a 
criticism of the guaiacum reaction and similar tests. 
In what follows, therefore, an attempt has been made to condense 
and arrange this vast amount of material under several heads: First, 
nature and general theor}^ of the color tests for blood;’’ second, 
‘^Substances other than blood which show the guaiacum reaction and 
similar tests;” third, “Substances which do not give the guaiacum 
reaction and similar tests;” fourth, “The delicacy of the chemical 
tests for blood;” and fifth, “The value of the guaiacum reaction and 
similar tests;” and to give under each topic considered all references 
obtainable to the original literature on the subject for the benefit of 
those seeking further information on any of the subjects herein 
})resented. 
THE NATURE ANd'gENERAL THEORY OF THE COLOR TESTS FOR 
BLOOD. 
The guaiacum test for blood and all similar reactions depends 
upon the oxidation of guaiacum or some other chromogenic substance 
to guaiacum blue or some other colored derivative, by ozonized oil 
of turpentine, hydrogen peroxide, or some other oxidizing agent hav- 
ing the properties of a peroxide, under the influence of blood, or more 
especially of the iron-containing blood pigments, as oxygen carriers. 
Among all of the chromogenic substances thus far employed in test- 
ing for blood, guaiacum has been the most extensively used. No 
fewer than 107 out of the 212 references to the literature of blood 
testing given at the close of this article have to do with the use of 
guaiacum in this connection. 
Among the other chromogenic substances which have been em- 
ployed for this purpose may be mentioned the following: 
Guaiaconic acid; Doebner, 46; Schaer, 140. 
Aloin; Buckmaster, 29; Einhorn, 49; Heuberger, 69; Jaworski and Korolewicz 
75; Klunge, 88; Koziczkowski, 91; Rossel, 137, 138; Schaer, 141, 142; 
Zuelger, 212. 
Benzidin: Adler, 2; Ascarelli, 7; Einhorn, 49; Jaworski and Korolewicz, 75; 
Lob and Mulzer, 108; Messerschmidt, 113a; Schlessinger and Holst, 143; 
Schumm, 159, 161, 162,163; Schumm and Westphal, 164; Utz, 192. 
The leuco-base of malachite green; Adler, 2; Buckmaster, 30; Czyhlarz and Von 
Filrth, 43. 
Phenolphthalin; Delearde and A. Benoit, 16; Kaatle and Amoss, 80; Meyer, 114; 
Pozzi-Escot, 128; Utz, 191. 
