Abstract
With a low impedance, transistor measuring circuit, the response of a platinum-platinum black electrode to hydrogen in solution is found to be linear with concentration. Hydrogen in solution can he qnantitated by this circuit. This offers the possibility of quanti tation of hydrogen by an intravascular plati num electrode. It may now be possible to quantitate, as well as detect, intracardiac shunts and repeat the observation without the withdrawal of blood.