The older readers will remember that, when they studied geography, Bolivia had a stretch of sea coast along the desert of Atacama. For a considerable time after independence was secured little attention was paid to Atacama, since it was regarded as worthless for colonization. Chile claimed sovereignty, and its jurisdiction was generally recognized. The year 1840 brought a change. In that year the wealth of fertilizer along that coast began to be exploited. Disputes soon arose between Chile and Bolivia as to the boundary line. The various claims made by Bolivia were inconsistent. War threatened, and diplomatic relations between the two countries were broken off. The outbreak of hostilities between Spain and Peru united the two countries against what they considered a common enemy. A treaty was drawn up in 1866 by which the 24th degree of south latitude was agreed upon as the actual boundary, although the Chileans were allowed to continue their operations in the nitrate regions beyond that line. Furthermore, Chile was to pay over to Bolivia half the customs received between the 24th and 25th degrees, and Bolivia was to hand over to Chile half the customs received between the 23rd and 24th degrees, south latitude. It was also provided that neither party to the treaty could alienate its rights to a foreign government. [Illustration: DIGGING NITRATE.] This treaty gave rise to continual disputes. Chile regarded this settlement as a final solution of the dispute, but Bolivia refused or neglected to live up to her part of the agreement. By a later treaty Chile renounced her claims between these two degrees, with the agreement on the part of Bolivia that the export duties on mineral products from that zone should not be increased, and that Chilean industries and citizens should not be subjected to higher taxes than then prevailed. This treaty was to remain in force for twenty-five years. The capital invested in that zone was almost exclusively Chilean, and the labourers employed were also of that nationality. Peru had large interests in the nitrate industry and began to intrigue with Bolivia, in order to prevent a ruinous competition in the market. So long as Chilean enterprise was left free this monopoly was impossible. As the interests of Peru and Bolivia were opposed to those of Chile, these two republics, in 1872, entered into a secret treaty of alliance. Like many state secrets this one became public, and Chile began to prepare for a conflict, which seemed impending, by purchasing ironclads and in other ways strengthening her navy.