In any industry where rates are made under conditions of monopoly rather than of free competition, it is imperative that cost of service be constantly held in view. Under conditions of free competition it is bound to obtrude itself automatically; but under monopoly it must oftentimes be forcibly invoked. The shipper whose manufacturing plant has once been located in a certain place is no longer free to accept or reject a certain rate. He can afford neither to move nor to abandon his works. In order to continue in business he must meet the prices made by competitors. This price may be made elsewhere under more favored circumstances. To a manufacturer an increase of freight rates instead of curtailing output, may lead to attempts to lessen the costs of production per unit by an enlarged output sold at cut prices. Under such conditions an enhanced freight rate is a positive deduction from profits without any gain to the consumer. It is impossible to trace any safeguard against extortion in the operations of a value of service law under such circumstances. An instance in point is afforded by a complaint of the Detroit Chemical works in 1908.[152] This company imported iron pyrites through Baltimore from Spain; that being the source of the bulk of the material used here in the manufacture of sulphuric acid. The Detroit Company sold its product throughout the West in competition with companies at St. Louis, Chicago and Buffalo. The companies at Chicago and St. Louis enjoyed low import rates by way of the Gulf ports. The Buffalo concern used to be favored by a low rate said to be due to canal competition on shipments from New York. Since 1903, however, the rate on pyrites from Baltimore to Detroit had been steadily increasing, from $1.56 to $2.72 per long ton. Even this latter rate by itself does not seem absolutely excessive, yielding a revenue of less than four mills per ton mile. But here again, it was not the absolute but the relative rate upon which the continued welfare of the industrial concern depended. The question had to be decided, not on the basis of cost, but from the point of view of the value of the service to the user. The carriers after this petition was filed voluntarily reduced the rate fifty-one cents per ton in January, 1908. The relative rate as compared with that to other competitive points was thus more equitably adjusted. The Interstate Commerce Commission on a review of the evidence held that this increase to $2.72 was unreasonable and unjust so long as it had been in effect; and awarded reparation to the amount of fifty-one cents per ton on all shipments made during its continuance.