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Note on the mode of coagulation of colloids—group coagulation
NOTE ON THE M O D E OF COAGULATION OF COLLOIDS--GROUP COAGULATION Tyoku Matuhasi and Kunio Aoto From the Institute of Physical and Chemical Research, Tokyo, Japan Received November 7, 1947
When a sol containing two different kinds of colloid particles, say A0 and B0, is caused to coagulate, the particles A0 and B0 are usually distributed at random in the resulting precipitate. This mode of coagulation may be called disordered coagulation (1). In serology, however, a sol containing two kinds of antigen-antibody complex, say A and B, when coagulated (agglutinated), the resulting precipitate consists of aggregates of A and B, each having a certain number of A only and of B only. To determine whether this mode of coagulation, which might be called group coagulation, occurs in the coagulation of colloids commonly known, we conducted a series of experiments and obtained some examples. The experimental details are given in each case. EXPERIMENTAL
1. Malachite Green ~ Methylene Blue Equal volumes of 0.5% malachite green and 0.5% methylene blue were mixed. No microscopic particles were observed in this mixture. The mixture was then coagulated by adding half its volume of (NH4)2MoO4.1 At first no precipitate was formed, but microscopically we observed green and violet aggregates having a size of about 1 ~. On standing overnight, a precipitate was formed in which green and violet aggregates were distributed at random. The green aggregates are similar to those formed when a malachite green solution is coagulated by addition of 1 N (NH4)2MoO4, and the violet aggregates are similar to those formed when a methylene blue solution is coagulated by addition of the same reagent. It is thought from the above observation that in the first stage of coagulation, the primary malachite green particles form green aggregates and the primary methylene blue particles form violet aggregates and these aggregates then clump together at random to form the precipitates. 1 The preparation of 1 N (NH4)2M004:90 g. of ammonium molybdate is dissolved in 100 cc. of 6 N ammonia solution, and 240 g. of solid ammonium nitrate is added. Water is added to the solution to make the volume 1 1. 63
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TYOKU MATUttASI AND KUNIO AOTO
2. Malachite Green ~ Methyl Violet A mixture consisting of equal volumes of 0.5% malachite green and 0.5% methyl violet was used in this experiment. No micr0scop~c particles were observed in this mixture. The mixture was coagulated by addition of one-half volume of 1 N (NH4)~MoQ. At first no precipitate formed, but. under the microscope we observed green and violet aggregates each having a size of about 1 tL. The aggregates are similar to those formed when malachite green or methyl violet is coagulated by addition of 1 N (NH4)2Mo04. From the above observation we see that the coagulation proceeds as in case (1). 3. Blood Charcoal Sol ~ Fe203 sol Blood charcoal was ground in an agate mortar, and to this was added human serum diluted 10-fold with water. This mixture was then diluted 20 times with water, The large particles of blood charcoal were separated by centrifugation. By this procedure we obtained a blood charcoal sol containing particles about i ~ in size. This sol showed electrolytic migration to the anode. The Fe~O3 sol was prepared by Buz~gh's method (2). The coarse particles of Fe~Os were removed by filtration. The sol thus obtained migrated to the cathode. •On mixing these sols, mutual coagulation takes place slowly. After a few days, precipitation takes place. Under a microscope, we observed that the precipitate consisted of two kinds of aggregates containing a certain number of charcoal par¢icles or of Fe2Oa particles ACKNOWLEDGMENT
The experiment was carried out in Dr. Katsurai's laboratory in the Institute of Physical and Chemical Research. We should like to express our sincere thanks to Dr. Katsurai for his generous support and valuable advice. SUMMARY If a sol containing two different kinds of colloid particles, say A and B, is coagulated, and the resulting precipitate is composed of aggregates consisting of a certain number of A and B particles, the phenomenon may be called group coagulation. This mode of coagulation has been observed in the coagulation of the following sols: (1) malachite green & methylene blue, (2) malachite green -F methylviolet, (3) blood charcoal -{- Fe~03 REFERENCES
] . FBEUNDLICH, H., KapiUarchemie,II, 209, AkaderaischeVerlagsgesellschaft,Leipzig,
1932. 2. v. BUZXGH,A., KoUoid-Z. 66, 130 (1934).
When a sol containing two different kinds of colloid particles, say A0 and B0, is caused to coagulate, the particles A0 and B0 are usually distributed at random in the resulting precipitate. This mode of coagulation may be called disordered coagulation (1). In serology, however, a sol containing two kinds of antigen-antibody complex, say A and B, when coagulated (agglutinated), the resulting precipitate consists of aggregates of A and B, each having a certain number of A only and of B only. To determine whether this mode of coagulation, which might be called group coagulation, occurs in the coagulation of colloids commonly known, we conducted a series of experiments and obtained some examples. The experimental details are given in each case. EXPERIMENTAL
1. Malachite Green ~ Methylene Blue Equal volumes of 0.5% malachite green and 0.5% methylene blue were mixed. No microscopic particles were observed in this mixture. The mixture was then coagulated by adding half its volume of (NH4)2MoO4.1 At first no precipitate was formed, but microscopically we observed green and violet aggregates having a size of about 1 ~. On standing overnight, a precipitate was formed in which green and violet aggregates were distributed at random. The green aggregates are similar to those formed when a malachite green solution is coagulated by addition of 1 N (NH4)2MoO4, and the violet aggregates are similar to those formed when a methylene blue solution is coagulated by addition of the same reagent. It is thought from the above observation that in the first stage of coagulation, the primary malachite green particles form green aggregates and the primary methylene blue particles form violet aggregates and these aggregates then clump together at random to form the precipitates. 1 The preparation of 1 N (NH4)2M004:90 g. of ammonium molybdate is dissolved in 100 cc. of 6 N ammonia solution, and 240 g. of solid ammonium nitrate is added. Water is added to the solution to make the volume 1 1. 63
64
TYOKU MATUttASI AND KUNIO AOTO
2. Malachite Green ~ Methyl Violet A mixture consisting of equal volumes of 0.5% malachite green and 0.5% methyl violet was used in this experiment. No micr0scop~c particles were observed in this mixture. The mixture was coagulated by addition of one-half volume of 1 N (NH4)~MoQ. At first no precipitate formed, but. under the microscope we observed green and violet aggregates each having a size of about 1 tL. The aggregates are similar to those formed when malachite green or methyl violet is coagulated by addition of 1 N (NH4)2Mo04. From the above observation we see that the coagulation proceeds as in case (1). 3. Blood Charcoal Sol ~ Fe203 sol Blood charcoal was ground in an agate mortar, and to this was added human serum diluted 10-fold with water. This mixture was then diluted 20 times with water, The large particles of blood charcoal were separated by centrifugation. By this procedure we obtained a blood charcoal sol containing particles about i ~ in size. This sol showed electrolytic migration to the anode. The Fe~O3 sol was prepared by Buz~gh's method (2). The coarse particles of Fe~Os were removed by filtration. The sol thus obtained migrated to the cathode. •On mixing these sols, mutual coagulation takes place slowly. After a few days, precipitation takes place. Under a microscope, we observed that the precipitate consisted of two kinds of aggregates containing a certain number of charcoal par¢icles or of Fe2Oa particles ACKNOWLEDGMENT
The experiment was carried out in Dr. Katsurai's laboratory in the Institute of Physical and Chemical Research. We should like to express our sincere thanks to Dr. Katsurai for his generous support and valuable advice. SUMMARY If a sol containing two different kinds of colloid particles, say A and B, is coagulated, and the resulting precipitate is composed of aggregates consisting of a certain number of A and B particles, the phenomenon may be called group coagulation. This mode of coagulation has been observed in the coagulation of the following sols: (1) malachite green & methylene blue, (2) malachite green -F methylviolet, (3) blood charcoal -{- Fe~03 REFERENCES
] . FBEUNDLICH, H., KapiUarchemie,II, 209, AkaderaischeVerlagsgesellschaft,Leipzig,
1932. 2. v. BUZXGH,A., KoUoid-Z. 66, 130 (1934).