In the paper she read a list of famous persons who had died in the course of the year. She read such utterly different names as Carnegie, Crookes, Emil Fischer, Habibullah, Laurier, Liebknecht, Osier, Patti, Rayleigh, Roosevelt. How hard they had tried, each in his own way, to be of some use in the world! Carnegie had given the world libraries, Crookes had warned it against famine, Fischer had endeavored to make foods, Habibullah had ruled his savages, Laurier had kept two races from biting each other, Liebknecht had wanted the poor to be comfortable, Osier had healed thousands, Patti had taken people’s minds off their troubles, Rayleigh had discovered something wonderful in the air, and Roosevelt had actually united two oceans. And how were they rewarded? Well, Habibullah and Liebknecht were assassinated, and Osier and Roosevelt robbed of their sons by war. If Dr. Osier and Colonel Roosevelt could speak to her now, would they advise her to marry? She did not believe that they would. Chapter 75 January of 1920 came, and the river was frozen over. The flowing oxygen was solid enough for men and horses to walk on. There they went in beaten paths, warm water trudging along on cold! Jean had always been amazed by such miracles, but their potency was doubled for her now, and they kept her from breaking her heart. Twice a week she and the dog tramped up the ice to the post-office, always with the hope of not hearing from Marvin. Any letter from him would mean that he had found a new girl. She ought to be hoping for such a letter, but somehow her wicked heart declined to hope. In her little laboratory she was perfectly free to risk her neck with any experiment she chose. And considering that she had got the oxygen from potassium chlorate, and that Horatio had barely missed passing out by chlorine before he met his death by other forces, she found herself wishing to see chlorine. She read that it was usually a green gas, though it could be liquefied and stored in steel tanks. She read that it combines with sodium to make table-salt, though how a green gas could come to look so sparkling white she did not understand. At first she thought she would coax it out of salt, but having no electric battery she had to abandon that plan. It was like fluorine and bromine, curious things of which she knew nothing. It was also like iodine, with which people paint themselves on the slightest provocation, though she suspected that soap and water will ordinarily do as well. It was furthermore related in some mysterious way to a heavy metal called manganese. She had not the faintest suspicion that manganese conceals twenty-five charges of electricity, or that its two undiscovered relatives conceal forty-three and seventy-five respectively. But her book gave her to understand that chlorine can easily be extracted from manganese chloride.