Question: when did the british first use gas in ww1
[{'answer': '25 September 1915', 'provenance': [{'wikipedia_id': '167578', 'title': 'Chemical weapons in World War I', 'start_paragraph_id': 23, 'start_character': 63, 'end_paragraph_id': 23, 'end_character': 80, 'bleu_score': 1.0, 'section': 'Section::::History of poison gas in World War I.:1915: Large-scale use and lethal gases.:British gas attacks.\n'}]}, {'provenance': [{'wikipedia_id': '167578', 'title': 'Chemical weapons in World War I', 'start_paragraph_id': 23, 'start_character': 0, 'end_paragraph_id': 23, 'end_character': 904, 'bleu_score': 0.9141466128402701, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 16148484162444706416}, 'section': 'Section::::History of poison gas in World War I.:1915: Large-scale use and lethal gases.:British gas attacks.\n'}]}]