The innumerable calamities which overtook Spain under Philip IV. (1621-65) and Charles II. (1665-1750) led to an immense introduction of billon money, to so great an extent, indeed, that it fell to one-eighth its previous value, thereby only complicating and increasing the evils. The result was an increasing premium on good monies, coupled with the usual disappearance of them. By the proclamation of 8th March 1625 it was prohibited, on severest penalties, to carry such premium above 10 per cent.; by the succeeding proclamations of 30th April 1636 and 7th September 1641 this limit was raised respectively to 25 per cent, and 50 per cent.
Philip IV. also instituted the first change in the silver system which it underwent since the great reform of 1497.
The tale was increased from 67 to 83 3⁄4 per mark, the real of eight being henceforth issued at an equivalence of 10 reals.
This change was equivalent to a reduction of 25 per cent. in the silver monies.
Under Charles II. this corruption proceeded in an ascending scale until 1680, when the gold doblon had arrived at an equivalence of 110 reals of billon, and the real of eight to 29 reals of billon.
By the law of 14th October 1686 an attempt was made to re-create and reform the tottering system. The mark of silver (11 din. 4 grs. fine) was to be coined at a tale of 84 pieces. The real of eight received a new name, Escudo de plata, and was to issue at an equivalence of 10 reals of the new silver.
The effect of this apparent reform was to lower the weight of the silver money 25 per cent., to incorporate the premium of 50 per cent. on the billon money, and to institute or sanction a matter of four separate monetary units:—
1. The real of old silver = 1⁄67 mark.
2. The real of new silver = 1⁄84 mark.
3. The real of billon = 1⁄126 mark.
4. The real of billon = 1⁄38 of the double escudo.
At the close of the reign the monetary system was as follows:—