The influence of the sugar trust may be studied by what is known as the method of differentials. The differential in sugar is the difference between the cost of the raw sugar and the refined granulated sugar. Raw sugar is the main material and the principal fluctuating item of cost beyond the control of the trust. Changes in the differential reflect the changes in profits except as modified by a cheapening of the process. The period from 1880 to 1887 was one of great competition. In 1880, the differential was one and ninety-two hundredths cents on each pound of refined sugar, but it fell steadily till, in 1887, it had reached sixty-four hundredths cents. In the fall of that year the trust was formed; and the next year the differential had risen to one and twenty-five hundredths cents, in 1889 to one and thirty-two hundredths cents. Tempted by the enormous profits, the rival refineries of Claus Spreckel were started, and with competition the differential fell, in 1890, to seventy hundredths cents. The rival factories were then bought up and under the new combination the differential went sailing up to one and three hundredths in 1892, and to one and fifteen hundredths in 1893. Rival factories again arose and competition grew stronger, reducing the differential to ninety-four hundredths in 1894. It was in that year that the firm of Arbuckle Brothers and Claus Doscher each opened a great refinery, and in the next year the differential fell to fifty hundredths cents. In 1900, some agreement, the terms of which were unknown to the public, was entered into by the rivals and the differential had risen, in March, 1901, to ninety-five hundredths cents. In every case the differential fell when competition was effective and went up when monopoly power was regained. [Sidenote: The nail trust] The differential of steel-wire nails is the difference between the cost of the steel billets and the price of the wire. Between 1890 and 1895 there was a steady decline in the differential. In 1895 was formed the nail pool, an agreement to share the profits, a form of combination. A rapid advance took place, both in the price and in the differential. In the fall of 1896 the pool was broken and then occurred a fall in prices and in the differential during 1896-97. In January, 1899, the nail trust was formed, controlling sixty-five to ninety-five per cent. of the output of wire nails, and a rapid advance occurred in the price and also in the differential. [Sidenote: The tin-plate trust]