Meantime they both enthusiastically gathered specimens, loading themselves and going so far out that they became drenched on their way back. Lazare went on pouring forth explanations, repeating all that his master, Herbelin, had told him. The ocean was a vast reservoir of chemical compounds, and the sea-weed was ever condensing in its tissues the salts contained in the water. The problem they had to solve was how to extract from the sea-weed all its useful components at small cost. He talked of taking the ashes which resulted from combustion--the impure soda of commerce--of sifting them, and finally extracting in a state of perfect purity the various iodides and bromides of sodium and potassium, the sulphate of soda, and the various salts of iron and manganese, so as to turn every particle of the material to profitable use. He waxed particularly enthusiastic over the fact that by the system which the illustrious Herbelin had devised nothing that could be of the slightest use would be lost. So there was an immense fortune before them. 'Good gracious! what a mess you're in!' cried Madame Chanteau, when they got home again. 'Never mind about that,' said Lazare gaily, as he flung his load of sea-weed on to the middle of the terrace. 'We are bringing you back five-franc pieces.' The next day one of the Verchemont peasants was sent with a cart to bring back a whole load of weed, and the experiments were commenced in the big room on the second floor. Pauline was appointed assistant. For a month they went quite mad over the subject. The room was soon crammed with dried weeds, with jars containing floating sprays, and instruments of all sorts of odd shapes. There was a microscope on the table, and the piano was hidden beneath retorts and flasks; whilst the wardrobe groaned with the weight of technical works and collections that were perpetually being referred to. The experiments, made with small quantities of material with the most scrupulous care, gave encouraging results. Herbelin's cold system was based upon the discovery that certain bodies crystallise at very low temperatures, and the only thing required was to obtain the necessary lowness of temperature, whereupon each particular substance deposited itself in crystals successively, and thus separate from others. Lazare burned the weeds in a pit, mixed the ashes with water, and subjected them to the necessary temperature, which he obtained by a refrigerative method based upon the rapid evaporation of ammonia. He would afterwards have to carry out these operations on a large scale and transfer them from the laboratory to proper works, observing careful economy in the method of manufacture and the installation of the requisite plant.