The Sun. — 1849-06-30 (London, England)

POLAND. The Emperor of RUSSIA arrived at Warsaw on the 27th, and, at his instigation, the Austrians at Cracow, seized the son of DEMBINSKI, and have detained him as a hostage for his father. We take note of this fact, because, in the event of the Hungarians making reprisals, it is as well to have an accurate record of the first aggressive act of the first aggressor. If what has hitherto been a system of comparatively speaking honourable warfare should henceforth degenerate into a system of murder and assassination, the responsibility will rest with the Emperor of RUSSIA, and should any of his sons be on any occasion seized by Poles, Hungarians, or Republicans, and kept as a hostage for his conduct, he will only have himself to thank for it. Warned by the experience of last year, the people should henceforth mete to the absolutist Sovereigns with their own measure.  DENMARK AND THE DUCHIES  The Danish Minister of War has officially announced the occupation of Aarhuus by the German troops on the 21st, and their advance northwards towards Spoerring. The steamer Hertha and some gun-boats fired at the German troops on their advance to the north of Aarhuus, on which the Germans sent a flag of truce to declare that if the firing from the vessels did not cease, they would destroy the town. The gun-boats then abstained from further cannonading, and, the account adds, so long as the Germans do not advance further northwards in that part, the vessels will not molest the troops. _ .  From Aalborg, of the 231, they state that in the direction of Randers, which lies more to the westward, the German forces had advanced as far north as Oersum and Hadberg. General PUITTWITTZS head-quarters were advanced to Skanderborg.  In the duchies and at Schleswig there is much dissatisfaction expressed by the leader of the antiDanish party, because the stadtholders have not been consulted or informed about the negotiations which it is allowed by all are still being carried on in Berlin ; and M. HARBOU declared, in answer to interpellations in the Assembly of the Schleswig States, on Saturday last, that the Government had not been able to obtain any participation in the negotiations in Berlin, or any official communication respecting their purport or nature.  - At the encampment before Fredirica a truce of arms has been commanded, and, indeed, came into force de facto. The firing has now ceased on both sides, and in all probability will not be recommenced by the German troops, who have received orders not to act on the oft'ensive, but merely to return the Danish fire. The latter show no intention to begin fire, but appear to be extremely active in repairing their fortifications and trenches. Many are of opinion that the present cessation of arms will terminate in a protracted armistice. It was stated at Copenhagen on the 22d, that Russia has proposed the partition of Schleswig into two portions ; the whole duchy to the north of thq Schlic to be incorporated into Denmark, while th smaller southern division shall be combined wit Holstein.  Denmark, it is said, refuses to accept this conditio The Danes have taken possession of the city Varde.