With the fall of the reign of Isabel II of Spain, a revolutionary period started, where all the structures (politics, economic and social) were trying to be updated. Within this modernisation, the most important currency system reform was introduced, undertaken in the modern and contemporary ages: the Order of 19th October of 1868.
This order puts to an end, the anarquic period where issuings from early centuries and the modern issues and reforms done during the reign of Isabella II, coexisted. This reform adopted, the model of the Latin Union, based in the metric system created by Napoleon and implemented by France, Belgium, Italy and Greece. All the coins issued by these countries were minted under the same alloy, weight and nominal values, both fractions and higher follow the ratio 1, 2, 5 and 10 (francs, lira, drachmas, pesetas…). We can observe that the monetary unit of all these countries weighs 5 gm, with a silver alloy of 835 thousandth. This, marked a great advance in the commercial and economic relationships between the countries within the Union. This was the early European Economic Union. The meaning of this introduction is to explain the weight of 33,26 gm of this assay of 100 pesetas of gold from Amadeus I. Following the model stablished by the Latin Union, the weight of this coin should have been 32,5 gm, as can be observed in posterior coinings of this value (e.g. 100 pesetas from 1897 of Alphonsus XIII). Starting from the base that 20 gold francs (the same for 20 gold pesetas, 20 gold liras, 20 drachmas, …etc.) weight 6,45 gm, a simple multiplication by 5 gives us the weight of the 100 pesetas.
