Biogragraphy
Bhoganāthar or Bhogar Siddhar, the Jñāna Guru of Babaji, in the poem “Bhogar Jñāna Sagarama” (Bhogar’s Oceanic Life Story, consisting of 557 verses, verse number 2, lines number 3 and 4), identifies himself as a Tamilian, (Ramaiah, 1979; 1982. p. 17). In the same verse he states that the great Siddha Kālangi Nāthar initiated him in Jñāna Yoga (supreme self-knowledge).
some believe that Bhogar was Lao Tzu.
He was a yogi and a sidhar (herbal healer) belonging to the caste of goldsmiths, who became a siddhapurusha under the guidance of Kalangi Nathar. In Bogar's Saptakanda he reveals details of various medicinal preparations to his disciple Pullippani (so named as he is believed to have wandered in the forests atop a puli or tiger) and at every stage he quotes his guru as the authority. Also Pulippani must have been a young man then, as he is often referred to as a balaka.
It is said that as per the last wishes of his guru, Bhogar proceeded to China to spread the knowledge of siddha sciences and his journey is said to have been made with the aid of an aircraft; he demonstrated to the Chinese the details of the construction of the aircraft and later built for them a sea-going craft using a steam engine. The details of these and other experiments demonstrated by Bhogar in China are documented in the Saptakanda.
Bogar's guru, Kālāngi Nāthar, is believed to be a Chinese who attained siddhi in South India and thus became included among the Eighteen Siddhars.
His disciple Pulipani siddhar took over the job of Lord Murugan pooja after Bogar went into Nirvigalpa Samadhi - the highest samadhi stage; where the Mind dissolves with Matter and Energy.
Teachings
Bogar anticipating that in due course of period, human beings will suffer from large number of disease. As an expert in medicine he used 4448 rare herbs and made 9 poisonous medicine, mixing these 9 poisons into one needs great knowledge and skill, to make a Master Medicine ( One medicine to cure all disease ). Thirumoolar also discuss one such Master Medicine in his book Thirumandhiram. With the consultation of Agasthiar ( Father of Ayurvedic Medicine) and other siddhars Bogar mixed the 9 poisons ( Nava Bashanam ) and made the Master Medicine in the form of Lord Murugan which is currently worshiped at Palani Murugan temple. There is a place near Palani Hill called Thanasiappan Temple which is the place were Bogar mixed the Nava Bashanam and made the Murugan idol.
Bogar and others then decided that by using the milk and panchamirtham ( a sweet recipe ) poured on the idol, one can extract the medicine from the idol. The milk and panchamritham then becomes medicine to cure disease. After installing Lord Murugan Navabashana idol at the Palani Hill, Bogar used to worship it with milk abishegam ( pouring milk on the idol ) and panchamirtha abishegam ( pouring panchamirtham on the idol ).
Bhogar Samadhi
source: http://www.gurusfeet.com/guru/bhogar-siddhar#tabset-4