(By Kate Carlisle)Vatican City, March 12 - Black smoke appeared over the Vatican following the first day of the cardinals' conclave to elect Benedict XVI's successor on Tuesday, signalling that a new pope had not been chosen. Thousands of onlookers expressed disappointment after hours of waiting in stormy Roman weather to see if white smoke would indicate that a new pope had been elected. Cardinals will gather on Wednesday morning in the Sistine Chapel, when the second day of the conclave to elect the new pope begins. The 115 cardinals assembled at the Vatican to elect a new pope were locked into the conclave for the first voting session in the afternoon. If one cardinal had received a two-thirds majority, or 77 votes, in the first round, a new pope could have emerged by the end of the day, though all sources predicted that it was very unlikely. The conclave officially began when the master of papal liturgical celebrations uttered the Latin phrase "extra omnes", or "everyone out", referring to anyone present who was not a cardinal-elector. The days leading up to the conclave saw an increase in some of the cardinals' social media activity. The archbishop of Boston, Cardinal Sean O'Malley, registered the biggest increase in activity on his Twitter account, according to figures published on Tuesday. The Capuchin Franciscan saw his activity increase by 52.6% over the last week, followed by Cardinal Wilfrid Napier, archbishop emeritus of Durban, at 49.5%, and Cardinal Roger Mahony, the controversial former archbishop of Los Angeles, at 33.4%. The figures came from social-media-monitoring platform ECCE/Customer. However Cardinal Luis Antonio Tagle from the Philippines seemed to be the most appealing to users of social media, according to the source. The 55-year-old archbishop of Manila clocked up some 104,809 social-media activities in the week leading up to the conclave, translating to around 50% of the share. Other particularly active cardinals included Timothy Dolan, archbishop of New York, and Gianfranco Ravasi, president of the Pontifical Council for Culture. Cardinal Odilo Scherer, archbishop of Sao Paulo, also saw a surge in popularity as a result of media interest in his possible election as pope. In any event the 115 cardinal electors taking part in the conclave are now obliged to refrain from any form of communication with the outside world until a new pope has been elected. A protester from the Ukraine-based feminist group FEMEN was detained by police for demonstrating topless in St Peter's Square outside the Vatican at the start of the conclave to elect a new pope. "Pope no more!" she shouted as police carried her away. Last month, shortly after Benedict XVI announced he would become the first pope in 600 years to abdicate, eight bare-chested members of the group stormed the Notre Dame cathedral in Paris to "celebrate the pope's farewell", according to French media. The conclave was called last month following the shocking announcement from Benedict that he would abdicate, becoming the first living pope to leave the throne of St. Peter in 600 years.