Circumstances conspired against his tottering loyalty.  The peace which Europe now enjoyed encouraged the circulation of discoveries and scientific ideas acquired during the war by the learned of various countries, who for nearly twenty years had been unable to hold communication.  Science was making great strides.  Claes found that the progress of chemistry had been directed, unknown to chemists themselves, towards the object of his researches.  Learned men devoted to the higher sciences thought, as he did, that light, heat, electricity, galvanism, magnetism were all different effects of the same cause, and that the difference existing between substances hitherto considered simple must be produced by varying proportions of an unknown principle.  The fear that some other chemist might effect the reduction of metals and discover the constituent principle of electricity,—­two achievements which would lead to the solution of the chemical Absolute,—­increased what the people of Douai called a mania, and drove his desires to a paroxysm conceivable to those who devote themselves to the sciences, or who have ever known the tyranny of ideas.

Thus it happened that Balthazar was again carried away by a passion all the more violent because it had lain dormant so long.  Marguerite, who watched every evidence of her father’s state of mind, opened the long-closed parlor.  By living in it she recalled the painful memories which her mother’s death had caused, and succeeded for a time in re-awaking her father’s grief, and retarding his plunge into the gulf to the depths of which he was, nevertheless, doomed to fall.  She determined to go into society and force Balthazar to share in its distractions.  Several good marriages were proposed to her, which occupied Claes’s mind, but to all of them she replied that she should not marry until after she was twenty-five.  But in spite of his daughter’s efforts, in spite of his remorseful struggles, Balthazar, at the beginning of the winter, returned secretly to his researches.  It was difficult, however, to hide his operations from the inquisitive women in the kitchen; and one morning Martha, while dressing Marguerite, said to her:—­

“Mademoiselle, we are as good as lost.  That monster of a Mulquinier —­who is a devil disguised, for I never saw him make the sign of the cross—­has gone back to the garret.  There’s monsieur on the high-road to hell.  Pray God he mayn’t kill you as he killed my poor mistress.”

“It is not possible!” exclaimed Marguerite.

“Come and see the signs of their traffic.”

Mademoiselle Claes ran to the window and saw the light smoke rising from the flue of the laboratory.

“I shall be twenty-one in a few months,” she thought, “and I shall know how to oppose the destruction of our property.”

In giving way to his passion Balthazar necessarily felt less respect for the interests of his children than he formerly had felt for the happiness of his wife.  The barriers were less high, his conscience was more elastic, his passion had increased in strength.  He now set forth in his career of glory, toil, hope, and poverty, with the fervor of a man profoundly trustful of his convictions.  Certain of the result, he worked night and day with a fury that alarmed his daughters, who did not know how little a man is injured by work that gives him pleasure.