Detention of goods in transit establishes release by payment or security, with notice, hearing and perishable goods safeguards. Detention and seizure of goods and conveyances in transit occur where transportation or storage contravenes the Act or rules; release is by payment of tax with prescribed penalties, reduced penalty if owner does not appear, or by furnishing prescribed security. The proper officer must serve an order and issue a notice specifying tax and penalty, provide an opportunity of being heard before determining amounts, and conclude proceedings on payment. Failure to pay within the prescribed period leads to further statutory proceedings, with the period subject to reduction for perishable or hazardous goods.