diff --git a/src/database/common_def.hpp b/src/database/common_def.hpp
index b9c7ade..210b66a 100644
--- a/src/database/common_def.hpp
+++ b/src/database/common_def.hpp
@@ -1,38 +1,74 @@
 /*-------------------------------------------------------
 
  - Module : database
  - File : common_def.hpp
  - Author : Fabien Georget
 
  Copyright (c) 2014, Fabien Georget, Princeton University
 
 ---------------------------------------------------------*/
 
 #ifndef SPECMICP_DATABASE_COMMONDEF_HPP
 #define SPECMICP_DATABASE_COMMONDEF_HPP
 
 #include <vector>
 #include <Eigen/Core>
+#include <exception>
 
 //! \file common_def.hpp common type definitions
 
 namespace specmicp {
 namespace database {
 
 
 //! ID of a species
 using id_species_t =  unsigned int;
 //! Vector containing a list of species (by ID)
 using list_species_t = std::vector<id_species_t>;
 //! Vector containing each strings
 using vector_labels_t = std::vector<std::string>;
 //! Stoechiometric coefficients for the reactions
 using reaction_mat_t = Eigen::Matrix<double, Eigen::Dynamic, Eigen::Dynamic>;
 //! Vector containing logK values
 using logK_vector_t = Eigen::Matrix<double, Eigen::Dynamic, 1>;
 
 
+
+//! \brief This error is thrown when a bad syntax is detected in the database
+class db_invalid_syntax : public std::exception
+{
+  std::string m_msg;
+  const char *m_msg_cstr;
+
+public:
+  db_invalid_syntax (const std::string &msg):
+    m_msg("DB Invalid Syntax :" + msg), m_msg_cstr(m_msg.c_str())
+  {}
+
+  const char *what() throw()
+  {
+    return m_msg_cstr;
+  }
+};
+
+
+//! \brief This error is thrown when the database is not as expected
+class invalid_database : public std::exception
+{
+  std::string m_msg;
+  const char *m_msg_cstr;
+
+public:
+  invalid_database (const std::string &msg):
+    m_msg("Invalid Database:" + msg), m_msg_cstr(m_msg.c_str())
+  {}
+
+  const char *what() throw()
+  {
+    return m_msg_cstr;
+  }
+};
 } // end namespace database
 } // end namespace specmicp
 
 #endif // SPECMICP_DATABASE_COMMONDEF_HPP
diff --git a/src/database/reader.hpp b/src/database/reader.hpp
index 20adf5c..15c90d9 100644
--- a/src/database/reader.hpp
+++ b/src/database/reader.hpp
@@ -1,147 +1,129 @@
 /*-------------------------------------------------------
 
  - Module : database
  - File : reader.hpp
  - Author : Fabien Georget
 
  Copyright (c) 2014, Fabien Georget, Princeton University
 
 ---------------------------------------------------------*/
 
 #ifndef DATABASE_READER_H
 #define DATABASE_READER_H
 
 //! \file reader.hpp Read the json database
 
 #include <jsoncpp/json/value.h>
 #include <memory>
 #include "data_container.hpp"
 
 namespace specmicp {
 namespace database {
 
 //! \brief Read a json file containing a database
 //!
 //! This is a reader class, it does not transform
 //!  (reduce to canonical form, swap the basis) the data
 class DataReader
 {
 public:
     //! Type of a smart pointer containing the database
     using DataContainerPtr = std::shared_ptr<DataContainer>;
 
     //! \brief Default constructor
     //!
     //! Be sure to set the path to the database using set_database_path
     DataReader() {
         data = std::make_shared<DataContainer>();
     }
     //! \brief Constructor
     //!
     //! @param filepath string containing the path to the database
     DataReader(std::string filepath):
         m_filepath(filepath)
     {
         data = std::make_shared<DataContainer>();
     }
 
     //! \brief Set the database path
     void set_database_path(std::string filepath){
         m_filepath = filepath;
     }
 
     //! \brief Parse database
     //!
     //! Throw db_invalid_syntax if a syntax error was detected.
     //! Throws std::invalid_argument if the path to the database is not correct
     void parse();
 
     //! Return the databes
     DataContainerPtr get_database() {return data;}
 
 private:
     //! \brief Parse the metadata section
     //!
     //! we don't do much with them for now....
     void parse_metadata();
     //! \brief Parse the basis section
     //!
     //! Contains the list of primary species
     void parse_basis();
     //! \brief Parse the aqueous section
     //!
     //! Contains the list of secondary species
     void parse_aqueous();
     //! \brief Parse the mineral section
     //!
     //! Contains the list of minerals
     void parse_minerals();
     //! \brief To be sure that the database is og
     void check_database();
     //! \brief Check the size of the basis
     void parse_size_db();
 
     std::string m_filepath; //! The path to the database
     Json::Value m_root;     //! Root of the json structure
 
     DataContainerPtr data;  //! The database to fill
 };
 
 //! \brief Parse an equation
 void parse_equation(const std::string &equation,
                     std::map<std::string, float>& compo);
 
 //! \brief Get the charge of a species by parsing the label
 //!
 //! Examples :
 //!     - neutral -> 0
 //!     - neutral[] -> 0
 //!     - charge[+] -> +1
 //!     - charge[-1] -> -1
 //!     - charge[+2] -> +2
 //!     - charge[2-] -> -2
 double charge_from_label(const std::string& label);
 
-
-//! \brief This error is thrown when a bad syntax is detected in the database
-class db_invalid_syntax : public std::exception
-{
-  std::string m_msg;
-  const char *m_msg_cstr;
-
-public:
-  db_invalid_syntax (const std::string &msg):
-    m_msg("DB Invalid Syntax :" + msg), m_msg_cstr(m_msg.c_str())
-  {}
-
-  const char *what() throw()
-  {
-    return m_msg_cstr;
-  }
-};
-
 //! \brief Check if a mandatory section/attribute exists
 //!
 //! Throw db_invalid_syntax if not.
 inline void check_for_mandatory_value(const Json::Value& root, const std::string& attribute)
 {
     if (not root.isMember(attribute))
     {
         throw db_invalid_syntax("Missing : mandatory parameter '" + attribute +"'.");
     }
 }
 
 //! \brief Return a mandatory section
 //!
 //! Throw db_invalid_syntax if the section does not exist
 inline Json::Value& get_mandatory_section(Json::Value& root, const std::string& section)
 {
     check_for_mandatory_value(root, section);
     return root[section];
 }
 
 
 } // end namespace database
 } // end namespace specmicp
 
 #endif // DATABASE_READER_H