The Musical Archive of the Cathedrals of Saragosse (E-Zac) keeps a relevant collection of manuscripts of keyboard music of the 18th century. The present study deals, for the fi rst time, with one of these sources, a miscellaneous one (E-Zac, A-1 Ms.1), in which we can find, together with a number of anonymous works, and copies of musical pieces by outstanding local and international composers, musical works by musicians who were developing their careers in the court of Madrid in the last two-thirds of the 18th century. Such were the cases of Domenico Scarlatti, father Antonio Soler, Manuel Blasco (de Nebra?), maybe José de Nebra, Fr. Joaquín Asiaín, (Juan de?) Sesé and José Moreno y Polo. The manuscript is particularly interesting not only for compiling three unknown adagios by Manuel Blasco, published here, but also for introducing some sonatas by Scarlatti and Soler, with amazing variants in comparison with the so called “authorized” or reference versions. This gives an added value to this kind of compilations –considered secondary up to now– with no doubt intended to be used by organist working in an ecclesiastical environment.